The basis of any inkjet printing process is the process of creating ink droplets and transferring these droplets onto paper or any other inkjet-compatible media. Controlling the flow of drops allows you to achieve different density and tone of the image.
To date, there are two different approaches to creating a controlled droplet flow. The first method, based on the creation of a continuous flow of drops, is called the method continuous inkjet. The second method of creating a flow of drops provides for the possibility of directly controlling the process of creating a drop at the right time. Systems using this method of droplet flow control are called systems pulse inkjet.
Continuous inkjet printing
The pressurized dye enters the nozzle and separates into droplets by creating rapid pressure fluctuations produced by some electromechanical means. Pressure fluctuations cause a corresponding modulation of the diameter and speed of the dye jet exiting the nozzle, which is separated into individual drops under the influence of surface tension forces.
This method makes it possible to achieve a very high rate of droplet creation: up to 150,000 droplets per second for commercial systems and up to a million droplets for special systems. An electrostatic deflection system is used to control the flow of droplets. Drops flying out of the nozzle pass through a charged electrode, the voltage on which changes in accordance with the control signal. The flow of drops then falls into the space between two deflecting electrodes having a constant potential difference. Depending on the previously obtained charge, individual drops change their trajectory in different ways. This effect allows you to control the position of the printed dot, and its presence or absence on paper. In the latter case, the drop is deflected so much that it enters a special trap.
Such systems allow you to print dots with a diameter of 20 microns to one millimeter. A typical dot is 100 microns, which corresponds to a droplet volume of 500 picolitres. Such systems are mainly used in the industrial printing market, in product labeling systems, mass label printing, medicine, etc.
Pulse inkjet printing
This principle of creating a flow of drops provides for the possibility of direct control of the process of creating a drop at a certain time. Unlike continuous systems, there is no constant pressure in the ink volume, and when a drop is needed, pressure pulses are generated. Controlled systems are fundamentally less complicated to manufacture, but their operation requires a device for creating pressure pulses approximately three times more powerful than for continuous systems. The performance of controlled systems is up to 20 thousand drops per second for one nozzle, and the droplet diameter is from 20 to 100 microns, which corresponds to a volume of 5 to 500 picoliters. Depending on the method of creating a pressure pulse in the ink volume, a distinction is made between piezoelectric and thermal inkjet printing.
For implementation piezoelectric method, each nozzle is equipped with a piezoelectric element connected to the ink channel by a diaphragm. Under the influence of an electric field, the piezoelectric element is deformed, due to which the diaphragm is compressed and unclenched, squeezing out a drop of ink through the nozzle. A similar drop generation method is used in Epson inkjet printers.
A positive feature of such inkjet printing technologies is that the piezoelectric effect is well controlled by the electric field, which makes it possible to accurately vary the volume of the resulting droplets, and therefore to a sufficient extent affects the size of the resulting spots on the paper. However, the practical use of drop volume modulation is hampered by the fact that not only the volume, but also the drop velocity changes, which causes point positioning errors when the head moves.
On the other hand, the production of printheads for piezoelectric technology turns out to be too expensive in terms of one head, so in Epson printers the printhead is part of the printer and can be up to 70% of the cost. total cost the entire printer. The failure of such a head requires serious service.
For implementation thermal jet method, each of the nozzles is equipped with one or more heating elements, which, when a current is passed through them, heat up to a temperature of about 600C in a few microseconds. The gas bubble that occurs during sudden heating pushes a portion of the ink forming a drop through the outlet of the nozzle. When the current stops, the heating element cools down, the bubble collapses, and another portion of ink comes from the inlet channel in its place.
The process of creating drops in thermal printheads after a pulse is applied to a resistor is almost uncontrollable and has a threshold dependence of the volume of the evaporated substance on the applied power, therefore, here, dynamic control of the droplet volume, in contrast to piezoelectric technology, is very difficult.
However, thermal printheads have the highest performance to unit cost ratio, so the thermal inkjet printhead is usually part of the cartridge and when the cartridge is replaced with a new one, the printhead is automatically changed. However, the use of thermal printheads requires the development of special inks that can evaporate quite easily without igniting and are not subject to thermal shock damage.
Lexmark print head
The print head of a black cartridge of a regular resolution of 600 dpi for early models (Lexmark CJP 1020, 1000, 1100, 2030, 3000, 2050) had 56 nozzles arranged in two zigzag rows. The print head for color cartridges of these models had 48 nozzles divided into three groups of 16 nozzles for each color (Cyan, Magenta, Yellow). The Lexmark CJ 2070 printer used a different printhead that contained 104 monochrome nozzles and 96 color nozzles.
Lexmark inkjet printheads, starting from the 7000 series, use printheads manufactured using laser nozzle-piercing technology (Excimer, Excimer 2). The first models of printheads contained 208 monochrome nozzles and 192 color nozzles.
For the Z51 model and the older model of the Zx2 and Zx3 family, a print head with 400 nozzles was developed. In the Z51 model, only half of the nozzles were used, and the rest worked in hot standby mode, when, as in the following models, all nozzles were simultaneously activated.
The lower and middle models of the Zx2 family use cartridges that are a modification of standard high-resolution cartridges, and the lower and middle models of the Zx3 family use new models of Bonsai cartridges.
Do not leave the print head nozzles open for a long time. If the nozzles are left open, the ink in them dries up and clogs the channels, which leads to printing defects. The cartridge should be left in the printer or in a special box (« garage»). It is also undesirable to touch the nozzles and contacts with your hands, as sebaceous secretions from the skin can spoil the surface.
Print head specifications
Period of meniscus formation:
This is the amount of time it takes for the chamber to refill with ink. It determines the operating frequency of the print head (from 0 to 1200 Hz).
Drop speed:
Low speed results in a continuous dot arrangement.
High speed results in spatter and streaks.
The mass of a drop is determined:
Heating element size.
Nozzle diameter.
Back pressure.
It has been noticed that in conventional inkjet printers, a drop of ink falling on the paper takes the form of a small triangle, so the lines look jagged on closer inspection. This is due to the fact that the drop is deformed in flight, and when it comes into contact with paper, it spreads. This is especially noticeable in low mode when printing economically. Lexmark offers printers with a new, advanced printing technology that balances nozzle shape and head speed so that ink droplets appear as regular strokes. This allows you to make the lines smooth, and the print quality is almost indistinguishable from laser printing. In addition, this shape of the spot avoids whitish streaks on the print.
What is ink?
Each manufacturer of inkjet printers develops and improves its ink composition, which is most adapted to the technology produced. At Lexmark, the main components of inkjet inks are:
- Deionized water (85-95% of total volume)
-Pigment or dye
- Solvent (for pigments)
- Humidifier (Humectant)
-surfactant (Surfactant)
- Biocide
-Buffer (pH stabilization)
Pigment or dye. Pigment-based inks (black only) are made from solid particles in a liquid. When such ink gets on paper, the liquid evaporates and is partially absorbed, and the powder sticks to the surface without spreading over it. Therefore, pigment-based inks are waterproof, have poor penetration into paper fibers, but are sensitive to light.
Dye-based inks are generally colored inks. The dye is soluble in water and is absorbed along with it into the thickness of the paper when it dries. Such ink dries faster than pigment ink, is light-resistant, but on the other hand gives more irregularly shaped spots on average than the latter.
Humidifier. The concentration of the humectant affects the viscosity of the ink. This setting should be optimal for the given ink formulation and the print head it will be used with. Indeed, on the one hand, the higher the viscosity, the worse the ink spreads over the surface of the paper, giving a smaller dot size and the clearer the image will be. On the other hand, too much viscosity leads to a long meniscus formation time, which degrades the printing speed. Typically, ink viscosity is a key parameter in determining the geometric channels in a printhead.
Surface tension affects the wettability of ink on all surfaces it comes into contact with, from the reservoirs in the cartridge to the surface of the paper. Too low static surface tension causes the ink to dry faster on the paper surface, but the average drop volume when the ink is squeezed out of the nozzles is too high. If the surface tension is too high, it will increase the drying time and therefore reduce the image stability when printing.
Acidity level(PH) low acidity leads to low solubility of the ink components in water and, as a result, poor water resistance of the image. The standard acidity level is considered to be in the range from 7.0 to 9.0.
Inside the cartridge there are ink reservoirs, print head nozzles and electrical contacts.
The color cartridge contains 3 separate cells for ink of 3 different colors. The monochrome cartridge contains only one black ink cell.
Inks and colors
The correct transfer of the color of an image to paper is a highly technological process that requires taking into account a considerable number of factors, including a subjective assessment. First of all, the color reproduction of the image depends on chemical composition ink and paper, printer architecture.
A mandatory requirement for ink is a very thin spectral composition, otherwise the colors obtained by mixing will be “dirty”. After drying, the ink must remain transparent, otherwise there will be no natural mixing of colors.
An important factor is also resistance to fading, environmental friendliness and non-toxicity.
It is believed that the optimal composition of the ink is already known. In almost all manufacturers, they represent a suspension of very small particles of mineral pigment. With color inks, the situation is worse, since it is very difficult to select mineral dyes of the desired spectral composition.
Currently, color rendering procedures are based on so-called color tables, which are used to convert color space, in which the original image was created, into some “deformed” color space, which takes into account the peculiarities of rendering colors on paper with ink. Usually, separate color tables are built for each type of paper and are optimized for each individual type of ink and printhead.
Lexmark Drivers
Lexmark printer drivers are ready to print when installed, with automatic object recognition to get good quality images without prior adjustment. Auto mode also allows you to achieve optimal combination document quality and speed. Setting the driver for special paper or selecting color tables for a more contrast or natural tone of the image is very easy in the Document Quality driver settings section.
Lexmark's Color Fine 2 Series drivers automatically detect the cartridge type, making it much easier to change all systems to a different cartridge type or change from an old one to a new one. A characteristic feature of this series of drivers is their ability to work with images in sRGB and ICM standards.
sRGB standard proposes that a device-independent color space is used to describe a color image, which is built into Microsoft OC or Internet tools. Using the standardized RGB description of the UTI-R BT.709 color space, this standard allows minimizing the transfer of additional system information associated with the color profile of the equipment on which the image was created along with the image. In the system part of the file with the image, only a reference is given to the standard in which it was created, and the destination position is actively used by the description of the color space provided by the operating system.
ICM standard allows you to more accurately define the variety of generation devices and the display of color images by using color hardware profiles for each type of image generating and display devices. However, this approach implies that the system information associated with the profile of the equipment on which the image is created is transmitted in place with this image.
Photo printing
A serious problem in inkjet printing is the correct reproduction of the light tones of the image. The fact is that conventional color solutions for inkjet printing produce image points of saturated color, so in order to obtain pale shades, ink drops need to be applied quite infrequently. This causes the spots to be so far apart when very light tones are reproduced that graininess becomes noticeable, and there is also a problem with reproduction in high tones.
One of the radical ways to solve this problem is to use additional light-colored inks. In this case, dark tones are obtained by filling with clarified ink. The cartridge with such ink usually replaces the second cartridge (black) and contains clarified Cyan, clarified Magenta and black inks. A light yellow tone is not used, since this color is perceived by the human eye without much difference as yellow.
Inkjet printers are among the most popular among consumers today. Moreover, in most cases, such a printer is bought as a peripheral to a home computer. There are reasons for that, and first of all low price and the ability to print color documents. Meanwhile, according to the sellers of a number of salons computer technology, most users have more than a vague understanding of the principles of inkjet printing. If everything is more or less clear to their owners with the work of dot-matrix or laser printers, then, as a rule, they can only say about inkjet printers that the picture is formed there by spraying small drops of ink on the paper.
To begin with, it is probably worth explaining what is such an indicator as dpi, which, it turns out, is more important than, for example, print speed. DPI (dot per inch, that is, dots inch) is the so-called number of drops per inch, a function of the frequency with which drops are ejected and the speed at which the printer's print head moves along the horizontal axis. A controlled nozzle at certain moments discretely ejects drops of ink and thus draws a line. The main challenge for a printer manufacturer is the combination of quality (maximum droplet emissions per line) and speed (minimum droplet emissions per line to achieve better high speed). Droplet ejection speed is from 10 to 20 thousand per second. By varying this frequency, or the speed at which the printhead carriage moves, it is possible to achieve optimal horizontal droplet density and hence print quality.
Resolution is a parameter determined by the size of the ink droplets. When applying smaller droplets, the clarity of the image will be higher when compared with an equal surface area filled with a smaller number of larger droplets. It is clear that in this case, higher quality will require a lower print speed, and vice versa.
Inkjet printers differ in the way they print.
Three main printing methods are quite widespread.
Thermal inkjet printing
The development of thermal inkjet printing technology began in 1984. The pioneers then were HP and Canon. But things went slowly, and for a long time it was not possible to come to the necessary results. Only in the 1990s was it finally possible to achieve an acceptable level of quality, speed and cost. Lexmark later joined HP and Canon to further develop thermal printers, leading to today's high-resolution printers.
As the name suggests, thermal (more correctly, electrothermal) formation of a jet is based on an increase in the temperature of liquid ink under the action of electric current . This temperature increase is provided by a heating element which is located in the ejection chamber. When heated, some of the ink evaporates, excess pressure quickly builds up in the chamber, and a small drop of ink is ejected from the ejection chamber through a precision nozzle. Within one second, this process is repeated many times. The most important thing for the success of this technology. this is to select the configuration of the ejection chamber, as well as the diameter and accuracy of the nozzle as accurately as possible. The behavior of the ink during heating and ejection from the nozzle, along with the characteristics of the ink itself (its viscosity, surface tension, ability to evaporate, etc.), is also influenced by the characteristics of the channel leading to the nozzle and the exit point to the nozzle. Of great importance for ensuring the correct ejection of ink from the nozzle are also the nature of the change in the ink meniscus in the nozzle after ejection and the refilling of the ejection chamber. Let us consider in more detail the stages of formation and ejection of a drop. The formation of a thermal ink jet begins in the print head of the cartridge. An electrical impulse generates a heat flux on the heating elements equivalent to more than two billion watts per square meter. This is about 10 times greater than the flow on the surface of the Sun. However, since the duration of the thermal pulse is only 2 millionths of a second, although the temperature at this time increases at a rate of 300 million degrees per second, the surface of the heating element only has time to heat up to about 600°C during this time. Since the heating is extremely fast, in reality the temperature at which the ink can no longer exist as a liquid is reached only in a layer with a thickness of less than one millionth of a millimeter. At this temperature (approximately 330°C), a thin layer of ink begins to evaporate and the bubble is forced out of the nozzle. The vapor bubble is formed at a very high temperature, and therefore the vapor pressure in it is about 125 atmospheres, i.e. four times the pressure generated in modern gasoline internal combustion engines. Such a bubble, which has tremendous energy, acts like a piston, ejecting ink from a nozzle onto the page at a speed of 500 inches per second. The resulting drop weighs only 18 billionths of a gram. By commands from the printer driver, several hundred nozzles can be activated simultaneously in any combination. The reservoirs from which ink is supplied to the print head can be divided into two constructive types. Firstly, a monoblock system is widely used, combining an integrated ink tank and an ejection unit. It has the advantage that the print head is replaced every time the ink tank is changed, helping to maintain high print quality. In addition, it is simpler in design and easier to perform replacements. In the second, constructively more complex system The print head is separated from the ink tank and only this tank is replaced when it is empty. The foam in the ink reservoir acts as a sponge to absorb liquid ink so that ink is continuously supplied to the print head, and there is neither unwanted gravity leakage from the cartridge nor ink leakage from the print head itself. On the basis of a monoblock cartridge there are electrical contacts and a print head. a key element of the entire inkjet printing process; ink is supplied to the print head through a set of channels coming from the reservoir. Printhead manufacturing. it is a complex process carried out at the microscopic level, where the accuracy of measurements is determined by microns. The main materials used for the ejection chamber, ink channel, electronic control circuit and heating elements are similar to those used in the semiconductor industry, where the thinnest conductive metal and insulating layers are precision laser processed. This technology requires large investments in both development and production, and this is one of the main reasons that very few companies venture into this area. The printhead is a collection of many micro-sets consisting of ejection chambers and associated nozzles, arranged in a checkerboard pattern in order to increase the vertical density of the nozzles. With this arrangement of nozzles, the number of nozzles at a distance of about 1.27 cm can reach 208, as is the case, for example, in the black cartridges of the Lexmark Z models, so that a resolution of 1.44 million dots can be achieved. Print quality is determined by many factors, but the main ones are. these are the dot size, the vertical density of the dots, and the frequency of droplet ejection through the nozzle; it is these indicators that are the main criteria for further work on printheads, whether they are thermal or piezoelectric heads. Thermal heads have some advantages over electromechanical ones, since the key technology for their manufacture is similar to that used in the manufacture of microprocessor chips and other semiconductor electronics products. Rapid progress in these areas is benefiting thermal technology, and even higher resolutions and faster print speeds can be expected in the coming years. Thermal inkjet printing has several advantages over competing piezo technology. For example, simplicity of design and close analogy with semiconductor manufacturing: this means that the marginal cost of production here will be lower than for a competing technology. The configuration of the ejection chambers allows the nozzles to be placed closer together, which makes it possible to achieve higher resolution.
Piezoelectric technology
Piezoelectric system created on the basis of an electromechanical device and brought to commercial readiness by Epson, was first used in Epson inkjet printers not so long ago. in 1993. Piezo technology is based on the property of certain crystals called piezocrystals (an example is quartz crystals in common quartz wrist watch), deform under the action of an electric current; thus, the term defines an electromechanical phenomenon. it physical property allows some materials to be used to create a miniature "ink pump" in which a positive to negative voltage change will cause a small volume of ink to be compressed and vigorously ejected through an open nozzle. As with the formation of an ink jet due to thermal effects, the size of the drop here is determined by the physical characteristics of the ejection chamber and the pressure created in this chamber due to the deformation of the piezocrystal. The change in the droplet size is carried out by changing the magnitude of the current flowing through the ejection mechanism. As with thermal printers, the frequency of the piezoelectric ejection depends on the potential frequency of the electrical impulses, which in turn is determined by the time it takes for the camera to return to its “quiet” state, when it is filled with ink and ready for the next work cycle. Piezo technology is highly reliable, which is very important because the print head, for purely economic reasons, cannot be part of a replaceable ink cartridge, as in thermal systems, but must be rigidly connected to the printer. For both thermal and piezoelectric systems, the performance is determined by many factors. The ability to change the size of the dot gives piezo technology certain advantages. On the other hand, piezo technology faces some purely physical limitations. For example, the large size of the electromechanical ejection chamber means that the vertical density of the nozzles must be less than that of thermal counterparts. Not only does this limit the prospects for further development, but it also means that to achieve higher resolution and uniformity in high quality printing, multiple passes of the print head over the same page are required.
A stationary printhead is somewhat cost-effective because it does not have to be replaced. However, this advantage is partially offset by the risk of air entering the system when changing the cartridge. This clogs the nozzles, reduces print quality, and requires several cleaning cycles to restore normal system performance. Another limitation so far for piezo systems concerns the use of dye-based inks: when using color (pigment) inks, which are of higher quality, but also have a higher density, there is also a risk of clogging of the nozzles. The piezoelectric print head, based on prior technology, has lower development costs, but is noticeably more expensive to manufacture. At present, the advantages of piezoelectric heads, such as high reliability and the ability to change the size of the drop, are very significant and make it possible to manufacture products of very high quality. However, as the price of thermal inkjet printers continues to drop and they increasingly take over the entry-level printer market, there remains a mid-range and high-end market for piezo systems.
Bubble jet printing
The Canon Bubble-Jet bubble-jet printing principle, invented in the late 70s, is ingeniously simple. In each nozzle, the thinnest channel in which droplets of ink are formed, there is a microscopic heater. Electrical pulses applied to it cause the ink to boil with the formation of air bubbles, and these bubbles push equal volumes of ink out of the nozzle with each pulse. Heating stops, the bubble disappears, a new portion of ink is drawn into the nozzle, and it is ready for a new cycle!
However, it took about 8 years for the first bubble inkjet printer to become available to users. In 1981, the promising Canon Bubble-Jet technology was first presented at the Canon Grand Fair and immediately attracted the attention of specialists. But it was not until 1985 that the first commercial model of the Canon BJ-80 monochrome printer appeared, and the first full-color BJ printer BJC-440 (A2 format, 400 dpi) appeared in 1988.
There are two main printing technologies on the market today for printing devices: piezoelectric and thermal inkjet.
Piezoelectric printing technology is developed on the ability of piezoelectric crystals to deform under the influence of electricity. Due to the use of this technology, it became possible to control printing, namely: to monitor the size of the drop, the speed of its exit from the nozzles, as well as the thickness of the jet, etc. One advantage of such a system is that the droplet size can be controlled. This ability allows you to get better images.
To date, experts have proven that the reliability of such systems is much higher than other inkjet printing systems.
When using this technology, the print quality is very high. Even universal and inexpensive models allow you to get images of the highest quality and high resolution. Also, the most important advantage of PU with a piezo system is high color rendering, which allows the image to look bright and saturated.
Epson technologies - time-tested quality
The printheads of EPSON inkjet printers are of high quality, and this is precisely what explains their high price. If you use a piezoelectric printing system, then you are guaranteed reliable operation of the printing device, and the print head does not dry out or clog due to the fact that it has minimal contact with air. The piezoelectric printing system was developed and implemented by EPSON, and only EPSON holds a patent for this system.
The thermal inkjet printing principle is used in Canon, HP, Brother printers. By heating the ink, they are transferred to the paper. By means of an electric current, liquid ink is proportionally heated, which is the reason for the name this method printing - thermal jet. An increase in temperature reproduces a heating element, which is located inside the thermal structure. With a strong increase in temperature, the main part of the paint evaporates, the pressure in the structure quickly rises, and a small drop of paint comes out of the heat chamber through a precision nozzle. This process is repeated repeatedly after one second.
The main disadvantage of the thermal inkjet method is that with such a printing technology, enough a large number of precipitation, which over time can disable it. Also, this scale clogs the nozzles over time, which leads to a loss in quality and print speed of the printer.
Also, devices that use thermal inkjet printing, due to constant temperature fluctuations, the print heads deteriorate, as it corny burns out under the influence of enormous temperature. This is the main disadvantage of such devices. The period of operation of the Epson PG MFP is absolutely identical to the service life of the device itself. This was made possible thanks to the high-quality materials from which the print head was developed. Customers who use thermal inkjet printing will often need to change the print head, as the high temperature will often cause it to burn out, which will greatly increase financial costs. The quality of the print head will also make a huge difference if users are using remanufactured cartridges.
Using an Epson inkjet printer in conjunction with refillable cartridges is very beneficial, as it improves the quality of the printer and reduces the cost of each printed image.
The print head of EPSON printers is of great importance not only for the stable operation of the printer. PG Quality allows you to increase print quality and print speed. Also, if the print head does not come into contact with air and dries out, the user will not have to change it, and therefore spend money in vain. Devices that use the thermal inkjet principle of operation can overheat greatly, and, accordingly, the print head can also overheat, which, if overheated, can simply burn out and get out of the standing.
As numerous checks and tests show, in order to print as economically as possible and at the same time be bright and effective, engineers recommend using EPSON printers with CISS. EPSON devices work much longer and more efficiently with the LF system than other similarly priced remote control units from other manufacturing companies.
Epson is a reliable manufacturer quality products which will make your work easier and more productive.
In a word, all the features of laser technology indicate its versatility and high efficiency - you can use such a printer both in the office and at home. The brilliant speed/quality ratio makes laser printers and MFPs indispensable in both large and small offices, as well as wherever large volumes of documents need to be printed. For example, students or educators who often print their work will be happy to be able to do more and get better quality materials.
For high speed color printing in enterprises, Konica-Minolta laser printers and MFPs can be recommended. Monochrome laser printing solutions for small and medium-sized offices should be found among Brother MFPs or Hewlett-Packard's line of budget LaserJet printers.
Laser technology involves a complex and finely organized printing mechanism - it uses static electricity and an optical system to create an invisible electrostatic prototype of the future print, and then "fill" it with toner particles and fix the result on paper.
First of all, the charging roller comes into action - it evenly covers the surface of the photoconductor with a negative charge. After that, the printer controller determines the areas on the surface of the drum that form the image. These areas are "illuminated" by the laser beam and the negative charge on them disappears.
Next, the feed roller gives the toner particles a negative charge and moves them to the developer roller, where they pass under the doctor blade, spreading evenly over the surface. Now, when in contact with the photoconductor, they fill with themselves those areas where there is no negative charge.
As a result, a visible image is formed on the drum - all that remains is to transfer it to paper and fix it. First, the paper is fed onto the transfer roller and receives a positive charge. When in contact with the photoconductor, it easily draws toner particles onto itself. Particles stick to paper only due to static electricity; to secure them in place, the sheet is processed in the fuser. This is the name of a system of two shafts, one of which heats the paper, and the other firmly presses it from below, allowing the molten toner particles to be imprinted deeper into the surface of the sheet.
Laser printers and MFPs very sensitive to quality Supplies Therefore, experts unanimously recommend using only original toner cartridges. Genuine toner has very small particles, which allows you to achieve high print quality and extend the life of the printer. Counterfeit toner can be compared to broken coal - it scratches the surface of the photoconductor and the internal parts of the printer with which it comes into contact.
The main disadvantages of laser printing are the high cost of the devices themselves and their cartridges, increased energy consumption, and ozone emission. Due to the more complex internal structure, laser devices are not as compact as inkjet devices.
The release of ozone during laser printing is inevitable, since the laser beam, when it comes into contact with air, splits oxygen molecules. And yet, manufacturers manage to reduce the volume of such emissions, minimizing the negative impact on humans. If you're looking for laser quality but are concerned about ozone, consider LED technology - it's similar to laser in many ways, but uses LEDs instead of a laser.
LED printing
The print quality is excellent - no graininess, and light and dark shades look equally natural. Laminated prints are resistant to fading and various external influences (water, fingerprints).
In addition to Canon, the release sublimation printers are engaged Sony and Samsung. The Sony DPP-FP55 features a large preview LCD, allows you to apply various effects and patterns to images (such as printing calendars), and uses proprietary Super Coat II lamination technology that can maintain original print quality for years to come.
Samsung SPP 2020B has its advantages: built-in Bluetooth module for mobile printing, simple but stylish design and the lowest cost per print in its class.
Users who have never experienced this technology often wonder why photos printed on a sublimation printer at 300x300 dpi look better than those printed on a laser printer at a much higher resolution. The secret is that for printing photographs, the priority parameter is not resolution, but lineature - the density of the printing screen.
Modern dye-sublimation printers such as the Canon Selphy have higher rates than many high-end photo inkjet printers. Hence the result - a dense raster structure, maximum clarity and, at the same time, smooth contours.
But what is the technological feature of sublimation printing? In this case, sublimation is the transition of a dye from a solid state to a gaseous state, bypassing the liquid state. The system is implemented quite simply: inside the printer are a heating element and a special film with a dye. A sheet of paper is placed between them. When heated, the ink evaporates from the film and enters the pores of the paper that have opened from heating. Further, the paper cools slightly, and its pores close, so that the image is firmly fixed on the sheet.
The peculiarity of sublimation technology is also that the paints of three colors are applied not at the same time, but in turn, so the print goes in three passes. An additional run for laminating pages is also possible. Lamination allows you to additionally protect prints from external negative influences and at the same time give them an attractive glossy sheen.
Vulnerability of sublimation technology - prints sensitivity to ultraviolet light. Now this problem is being overcome by developing a new type of ink. The main disadvantages of portable photo printers can be considered low speed and small print format. Ideal for holidays, but not serious for the office, as sublimation printers have a narrow specialization - photo printing, and, moreover, are not designed for a large flow of tasks.
Large volumes and high speed printing, combined with high reliability and ease of maintenance - the advantage solid ink printers.
Solid ink printing
Among the most relevant modern technologies printing, solid ink offers particularly wide possibilities for business use. Due to its cost-effectiveness and high-speed qualities, the solid ink printer is ideal for working with large volumes of color documents and provides high-quality high-speed printing, not always available even to the best laser devices. So, for Xerox ColorQube printers, the print speed can reach 85 ppm, and the first print is out in just 5 seconds.
The key feature of solid ink printers is that they are initially focused on high-speed color printing and at the same time the thousandth print is as clear and bright as the first one, because the print quality in this case does not depend on the number of printed pages. In addition, such printers print on paper of different weights with the same success.
A striking example of a modern solid ink printer is the Xerox Phaser 8560. This model is designed for medium workgroups. Applying four colors of ink at the same time allows you to achieve high speed color printing. The piezo elements of the nozzles provide a more intense droplet emission than inkjet printers. Melted ink is baked on paper instantly, without spreading or spilling, and is distinguished by enviable durability. During the passage through the machine, the paper does not have time to get very hot, so you can print the second side of the sheet immediately - without prejudice to the first.
Dry ink sticks - sticks - correspond to different colors of the CMYK system. They are easy to use and store: do not stain hands and clothes, do not dry out. The bar of each color, designed for a specific printer model, has its own unique shape, which allows you to avoid errors when installing it in the printer.
It is also worth noting the high reliability of solid ink devices - the design of the printing mechanism is very simple and contains a minimum of moving parts, which reduces the risk of breakage. The image drum in a solid ink printer is replaced approximately every five years. Modern models are equipped with a wide print head that requires little or no movement to cover the full width of the photoconductor. Little movement is required from it only at resolutions above 2400 dpi. Thus, the printing speed is high, and the wear of components is minimal.
Once upon a time, solid ink printers were considered very expensive, but by now their cost has dropped markedly. The printer has minimal impact on environment and does not emit ozone. It is also important that color solid ink printing costs almost half the price laser.
Preparation of solid ink printers for work takes place in several stages. First, the printhead tanks are heated to 140-180°C. At the same time, the melting of solid ink on the ceramic plates begins, as well as the heating of the metal photoconductor. Molten ink flows into the hot cavities of the print head. When the containers are full, the heating of the plates stops.
The next step is to clean the print head nozzles with a vacuum pump cleaning unit. Sliding close to the nozzles of the head, the cleaning unit pumps air out of them and absorbs some of the melted ink. Returning to his original position, he drains the hot ink into a special waste tray. There they harden again. The ready-to-use device is kept in a “warm state” so that the melted ink does not cool and solidify again.
The disadvantages are quite obvious. Each time the printer is turned on, a small amount of ink is emitted and about 5% of each cartridge is wasted. The warm-up process itself takes about 15 minutes, so frequent restarting of the device costs a pretty penny. Ideally, the printer should not be turned off at all - it is better to keep it in working condition all the time, just like the server. In the enterprise, this will not be difficult, especially since the device consumes very little energy in sleep mode.
If, however, the power suddenly turns off during printing, the nozzles may become clogged with solidified ink and you will have to clean it. Therefore, when the power supply is unstable, it is worth connecting the printer through a UPS (Uninterruptible Power Supply).
Solid ink documents are susceptible to temperatures over 125°C, so if you are preparing letterhead that will later be run through a laser printer, the ink may not withstand contact with the thermal roller of the laser fuser.
Another disadvantage of solid ink technology is that in color printing, light areas of a color image have a noticeable raster structure. The reason is that the ink drops are clearly fixed in place, and the nozzles are widely spaced. Therefore, despite good color reproduction, solid ink devices are not suitable for photo printing.
conclusions
So, let's summarize our conversation, once again briefly listing the features and scope of each of the printing technologies discussed above.
inkjet printing- finds application both in professional polygraphy, and in house conditions or at small office. It is used not only in desktop printers and MFPs, but also in plotters, as it is best suited for printing high-resolution color materials, including: photographs, advertising and souvenirs, geographical maps and technical documentation (CAD, GIS). Allows you to print on the surface of optical discs, which is very convenient for designing a CD / DVD collection. Another important advantage of inkjet devices is affordable price. The main disadvantages are low speed and high cost of printing; relatively high cost of ownership.
laser printing- the ideal choice for those who print often and in large quantities. A smart choice for the office, especially for medium to large workgroups. The most important advantages of laser devices are: high speed and low cost of printing, a good level of clarity and detail of images, resistance to high loads, “long-playing” toner, which, unlike liquid ink, does not spread and is stored for a long time. Disadvantages of the technology: the relatively high cost of devices, the release of ozone, the increased concentration of which worsens health. In addition, laser devices are not as compact as inkjet ones.
LED printing- in many respects it is similar to laser, it has the same advantages, but instead of a laser beam it uses an LED ruler, which reduces the cost of ownership of the device and completely eliminates the release of ozone. In LED printers using single-pass tandem technology, the speed is greatly increased and the quality of color printing is improved. Another technology, the ProQ2400, brings color print quality closer to photographic quality by setting different intensities for each color. The LED printer is really reliable in operation and is great for modern office especially for document-intensive organizations. The main disadvantage of the technology is that it is impossible to create two absolutely identical LED strips, which means that prints made on two printers of the same model will not be 100% identical. The difference is imperceptible to the eye, but with accurate measurements it is detected. In addition, in terms of point positioning accuracy, the LED ruler is still slightly inferior to the laser beam.
sublimation printing- the dream of an amateur photographer and vacationer. Whether you want to share vivid holiday memories with your loved ones or even create postcards and calendars from your photos, a sublimation printer will help you achieve what you want even without a computer. You can print photos directly from USB sticks, digital cameras and memory cards. Some sublimation printers are equipped with Bluetooth adapters, so you can print directly from mobile phone. And if you decide to connect to a computer, Wi-Fi will help you. Creating juicy, realistic photos with an excellent level of clarity does not require you to additional knowledge and effort. But do not forget that the scope of sublimation technology
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7 years ago
The most common printers today are based on inkjet technology: crushed dye droplets are sprayed onto the material. Typically, as in dot matrix printers, the print head moves across the media feed direction to form an image stripe, and then the media shifts to print the next stripe. However, instead of needles, the head has many nozzles for ejecting printer ink. There are two varieties of inkjet technology:
thermal jet, in which the activation of the paint and its release occur under the influence of heating;
piezoelectric, in which the ejection of paint occurs under pressure created by the oscillation of the membrane.
Piezoelectric inkjet technology
The piezoelectric system, based on an electromechanical device and commercialized by Epson (a subsidiary of Seiko), was first used in Epson inkjet printers in 1993.
Drop ejection system
Piezotechnology is based on the property of some crystals, called piezocrystals (an example is quartz crystals in now common quartz wristwatches), to deform under the influence of an electric current; thus, the term defines an electromechanical phenomenon. This physical property allows some materials to be used to create a miniature "ink pump" in which a positive to negative voltage change causes a small volume of ink to be compressed and vigorously ejected through an open nozzle. As with the formation of an ink jet due to thermal effects, the size of the drop here is determined by the physical characteristics of the ejection chamber (firing chamber) and the pressure created in this chamber due to the deformation of the piezocrystal.
Modulation, i.e., changing the size of the drop, is carried out by changing the amount of current flowing through the ejection mechanism. As with thermal printers, the frequency of the piezoelectric ejection depends on the potential frequency of the electrical impulses, which in turn is determined by the time it takes for the camera to return to its “quiet” state, when it is filled with ink and ready for the next work cycle. Piezo technology is highly reliable, which is very important because the print head, for purely economic reasons, cannot be part of a replaceable ink cartridge, as in thermal systems, but must be rigidly connected to the printer.
Advantages and disadvantages
For both thermal and piezoelectric systems, the performance is determined by many factors. The ability to change the size of the dot gives piezo technology certain advantages. On the other hand, piezo technology faces some purely physical limitations. For example, the large geometric dimensions of the electromechanical ejection chamber mean that the vertical density of the nozzles must be less than that of thermal counterparts. Not only does this limit the prospects for further development, but it also means that to achieve higher resolution and uniformity in high quality printing, multiple passes of the print head over the same page are required. A stationary printhead is somewhat cost-effective because it does not have to be replaced. However, this advantage is partially offset by the risk of air entering the system when changing the cartridge. This clogs the nozzles, reduces print quality, and requires several cleaning cycles to restore normal system performance. Another limitation so far for piezo systems concerns the use of dye-based inks (dye based inks): when using pigment inks, which are of higher quality, but also have a higher density, there is also a risk of clogging of the nozzles.
prospects
The piezoelectric print head, based on prior technology, has lower development costs, but is noticeably more expensive to manufacture. At present, such advantages of piezoelectric heads as high reliability and the ability to change the size of the droplet are very significant and make it possible to manufacture products of very high quality.
Vertical Resolution
The number of vertical positions is primarily related to the number of vertical nozzles on the print head (lines per inch). Since there are difficulties in creating a print head that includes elements that span two vertical lines at once, two separate rows of nozzles are placed next to each other. To achieve an acceptable print speed, the maximum number of lines must be printed during each pass of the printhead. In this situation, the manufacturer must make a trade-off between speed (higher print head and maximum number of nozzles) and production costs (minimum number of nozzles).
Horizontal Resolution
The number of horizontal positions, called drops per inch (dpi), is a function of the frequency at which drops are ejected and the speed at which the print head moves along the horizontal axis. A controlled nozzle at certain moments discretely ejects drops of ink and thus draws a line. The main difficulty for the manufacturer is the combination of quality (maximum droplets per line) and speed (minimum droplets per line to achieve higher speed). Droplet ejection speed is from 10 to 20 thousand per second. By varying this frequency or the speed of the print head carriage, the optimum horizontal droplet density can be achieved.
Physiological factors and color perception
The perception of the quality of a color document is closely related to the physiology of human vision. Taking into account some individual deviations, the human eye is able to distinguish only colors having a wavelength in the range from 380 nm (violet) to 780 nm (red). Within this spectrum, the human brain can distinguish about a million shades of colors (again with small individual differences). The perceived color spectrum plays an important role in visually evaluating differences in the quality of printed documents: printers capable of reproducing more shades of color will produce documents that human vision will subjectively attribute higher quality.
Number of colors
The total number of possible colors in which an elementary point can be colored corresponds to the number of addressable elementary colors. With three primary colors, you can get eight basic colors: cyan (Cyan), magenta (Magenta), yellow (Yellow), red (Cyan + Yellow), green (Yellow + Cyan), blue (Cyan + Magenta), white and black. . This system is binary in that color points may or may not be present. If we apply the halftone grayscale principle to these three primaries, thus creating color hues, we get 256 hues for each of the three primaries and thus 256 to the third power of possible color combinations per dot. In other words, this number is greater than what the human eye can discern.
Drop size
The drop size is a complex function of the pressure at which the ink is ejected and the diameter of the nozzle. Usually the droplet size remains unchanged. In certain cases, the size may change and this technology is known as variable droplet printing. There is a definite relationship between the size of the drop and the size of the dot reproduced on paper. Theoretically, a 20 picolitre drop would make a 60 micron dot (that's approximately one four hundredth of an inch), while a 2 picoliter drop would make a 30 micron dot barely visible to the human eye.
Resolution matrix M
Resolution is the parameter most easily manipulated quantification when determining the print quality of a document. Resolution measures the precision with which dots are placed on the page. The resolution matrix specifies for any given point the total number possible positions. With dual print head technology, there can be two different matrices, one for color printing and the other for black and white. The matrix allows you to create color levels for each elementary point. Since resolution is the result of combining two different technological processes, the horizontal and vertical resolution may differ. The latest advancement in inkjet printing is 2400 dpi horizontal resolution, which allows for 2400 print dots per inch of printed line, twice the standard currently in use. Thanks to the precision of printing and the microscopic droplet size of 7 picoliters, such high results are achieved that the image raster becomes completely indistinguishable for human vision. The 2400 dpi resolution is thus intended for printing documents that require the highest possible resolution and impeccable quality. Because print speed is highly dependent on the number of dots printed, printing at 2400 x 1200 resolution will be slightly slower than printing at lower resolutions.
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