A printer (from the English print; also called a printing device) is a computer peripheral designed to transfer text or graphics from electronic form onto a physical medium in small runs (from a few to a few hundred copies) without creating a printing plate. This is what distinguishes printers from commercial printing equipment and risographs, which, thanks to the printing plate, are faster and cheaper for large runs (hundreds of copies or more).

Multifunction devices (MFDs) have become widespread, combining the functions of a printer, scanner, copier and fax machine in a single unit. Such a combination is technically sensible and convenient in use.

Wide-format printers are sometimes incorrectly called plotters.

Classification of printers

By their ability to print graphical information, printers are divided into alphanumeric ones (able to print only a limited set of characters) and graphical ones.

By the principle used to transfer the image onto the medium, printers are divided into:

• impact character printers (alphanumeric printing units) - drum printers, printers based on a daisy-wheel print unit, or typewriters with an electromagnetic drive. Historical types. They became obsolete in the 1980s. They have not been manufactured since the early 1990s.
• dot matrix;
• laser (also LED printers);
• inkjet;
• dye-sublimation
• solid ink
• 3D printers
• volumetric thermal cutters

By the number of printing colors

• monochrome (single-color) ones
• color ones.

In color printers, the CMYK colors are used as the basis of the color model:

• Cyan
• Magenta
• Yellow
• Kobalt - black (the English name corresponds to the name of the heavy metal (cobalt) contained in black colorants)

In addition to the base CMYK colors, a color printer may be equipped with light inks (Light Cyan and Light Magenta), which increase the apparent resolution at low ink coverage. Besides these, orange and green (Orange and Green) are sometimes used, slightly widening the printable color gamut. Printers intended for printing on colored materials are additionally equipped with white.

By the connection to the data source (where the printer can receive print data from), or by interface:

• over wired channels:
  • via a SCSI cable
  • via a serial port
  • via a parallel port (IEEE 1284)
  • over the Universal Serial Bus (USB)
  • over a local area network (LAN, NET)
  • using two ports, where one of the ports controls the CNC drive and print head data goes through the other port
• by means of a wireless connection:
  • via an IR port (IrDA)
  • over Bluetooth
  • over Wi-Fi (including via AirPrint)

An IR connection is only possible with a device in direct line of sight, whereas the Bluetooth and Wi-Fi interfaces, which use radio waves, operate at distances of up to 10-100 meters.

Some printers (mainly inkjet photo printers) offer the ability to print standalone (that is, without a computer), having a flash card reader or a port for connecting a digital camera, which makes it possible to print photographs directly from a memory card or from cameras. Printers that support AirPrint technology make it possible to print documents and photographs directly from iOS-based mobile devices without a cable (the connection is made over Wi-Fi). AirPrint is available for the iPad, as well as for the iPhone and iPod Touch of the third generation or later.

A network printer is a printer that can accept print jobs (see Print queue) from several computers connected to a local area network. The software of network printers supports one or more special data transfer protocols, such as IPP. This solution is the most universal one, since it makes printing possible from various operating systems, which cannot be said of Bluetooth and USB printers.

By the type of material printed on:

• Roll-fed — equipped with systems for winding and unwinding roll material; intended for printing on self-adhesive film, paper, canvas and banner fabric

• Rigid sheet — for printing on PVC, polystyrene and foam board. The sheet of material is held on the bed by vacuum hold-down or with clamps. The carriage (equipped with a drive for movement along the X axis) is mounted on a gantry, which moves together with the carriage above the material (along the Y axis).

• Novelty (souvenir) — movement of the workpiece relative to the head along the Y axis is provided by the servo drive of a moving table; in addition, the table is equipped with a mechanism for adjusting the distance between the workpiece and the carriage (for printing on workpieces of different heights). They are used for printing on discs and phones, and for marking parts.

• Flexible sheet — for printing on paper and film of standard formats (A3, A4, etc.). They are equipped with a mechanism for picking up and feeding sheet material.

In addition, there are inkjet printers for 3D printing of three-dimensional shapes.

By the type of ink used:

• Water-based, using a water-soluble dye. Used in the vast majority of home and office inkjet printers and in some indoor wide-format printers. The main drawback is poor lightfastness, that is, rapid fading in sunlight.
• Solvent inks. Solvent inks are used in wide-format and indoor printing. They are distinguished by very high resistance to water and precipitation. They are characterized by the viscosity of the solvent, the graininess and the pigment dye fraction used.
• Alcohol-based — these have not come into wide use, since heads printing with alcohol-based inks dry out very quickly.
• Oil-based — used in industrial marking systems and for testing print heads.
• Pigment inks — used to obtain high-quality images, in indoor printing and in photo printing.
• UV-curable inks — used as an environmentally friendly replacement for solvent inks and for printing on rigid materials.
• Thermal transfer inks — the distinctive feature of thermal transfer inks is the ability, using a heat press, to transfer the printed image from a backing onto an article. They are used for applying logos to clothing.

By purpose, printers can be:

• Wide-format — the main purpose of wide-format printing is outdoor advertising. Wide-format printers are characterized by a large printing width (most often 3200 mm), high printing speed (from 20 m² per hour) and not the highest optical resolution.
• Indoor — the field of application of indoor printing is printing interior decoration elements, posters, information stands and drawings. The main format is 1600 mm. The main manufacturers of indoor printers are Roland and Mimaki.
• Photo printers — intended for printing photographs; they print on small-format materials (usually on rolls up to 1000 mm wide). The color model is no worse than CMYK+Lc+Lm (six-color printing); sometimes the color model is supplemented with orange, white ink, silver (to obtain metallic effects), etc.
• Novelty (souvenir) — used for printing on small parts, for printing on discs and on workpieces of complex shape. They are made by many companies: TechnoJet, Epson, Canon, HP, etc.
• Office — they differ from photo printers in their cheaper construction, in most cases the absence of light inks, and sheet feeding of the material. The main manufacturers of office printers are Epson, HP, Canon and Lexmark.
• Marking — these are built into production lines. The print head, fixed immovably above the conveyor belt, applies markings to the moving articles.
• Nail printers — used to apply complex designs to fingernails in nail-art salons.

By the ink supply system:

• Continuous, with the sub-tanks and heads located at the same level (the pressure at the head inlets is regulated by the height of the sub-tanks).

Structure: ink canisters → pump → filter → flexible duct → carriage → check valve → sub-tank equipped with ink level sensors → head.

• Continuous, with sub-tanks located above the heads. The pressure of the tall ink column on the heads is balanced by a vacuum system consisting of a vacuum pump and vacuum regulation devices.

Structure: ink canisters → pump → filter → flexible duct → carriage → check valve → sub-tanks equipped with ink level sensors and connected to the vacuum system → heads.

• Gravity-fed. The heads and the ink canisters are connected by tubes running through the flexible duct. The only intermediate element is a damper, which filters the ink and dampens the pressure fluctuations that arise when the flexible duct moves.

• Ink supply from cartridges that move together with the carriage. The main advantage of this system is its low cost. Its drawbacks are the small ink reserve in the cartridges, the added weight the cartridges give the carriage, and the slow drop in pressure at the head inlets caused by the falling ink level in the cartridges.

Dot matrix printers

The Amstrad DMP 3000 dot matrix printer

The Epson FX-85 dot matrix printer

The principle of image formation in a dot matrix printer

Dot matrix printers are the oldest of the printer types still in use; their mechanism was invented in 1964 by the Japanese corporation Seiko Epson.

The image is formed by a print head consisting of a set of pins (a pin matrix) driven by electromagnets. The head moves line by line along the sheet, and the pins strike the paper through an inked ribbon, forming a dot image.

The main drawbacks of dot matrix printers are that they are monochrome (although color dot matrix printers did exist, at a very high price), their high noise level, which reaches 65 dB, and their very low operating speed (when printing several copies, the lack of speed is successfully offset by the ability to print through carbon paper).

Interfaces — the standard bidirectional 8-bit IEEE 1284 parallel interface, and the RS-232 and USB serial interfaces.

High-speed line matrix printers are also manufactured, in which a large number of pins are evenly distributed on a shuttle mechanism across the full width of the sheet.

Despite having been completely displaced from the home and office spheres, dot matrix printers are still quite widely used in certain areas (printing sales receipts, banking — printing documents with carbon copies, etc.)

The inked ribbon.

The inked ribbon of a dot matrix printer is intended to hold a supply of colorant and to deliver the colorant to the print head.

During printing, the inked ribbon of a dot matrix printer is slowly wound on, delivering fresh colorant to the print head; ribbons come in two types — those closed in a loop (wound in one direction only) and ribbons of limited length, fitted with a reverse rewind mechanism. On some dot matrix printers, if the reverse rewind mechanism fails, a spent ribbon can be rewound by hand.

Over time the inked ribbon wears out mechanically — the print head literally cuts the inked ribbon lengthwise, in two. In some cases the service life of the inked ribbon can be extended by turning it over to the other side. If the ribbon is not yet worn out but the image has faded noticeably, the ribbon can be impregnated with fresh ink and the color will be restored. If a dot matrix printer is used extremely rarely, the inked ribbon suffers more from the colorant simply drying out than from mechanical wear. The printed images fade. A dried-out inked ribbon need only be impregnated with oil for lubricating household sewing machines and the color is restored.

Comparison with other types

• Print quality. Very low, comparable to that of a typewriter. Graphics are nevertheless possible.
• Color rendering. There were color dot matrix printers with a four-color ribbon, which could print in seven fixed colors. The yellow part of the ribbon became contaminated very quickly, degrading color rendering still further. Even so, in the 1980s this was the only way to print in color on the desktop.
• Print speed. For ordinary 9-pin and 24-pin printers, tens of seconds per page in text mode and several minutes in graphics mode. High-speed printers are several times faster. Printing through carbon paper and on self-copying forms is possible. Where a single copy has to be printed immediately (at ticket counters, for example), dot matrix printers still have no equal: a laser printer is still warming up while the dot matrix printer is already delivering the printout.
• Cost per page. Extremely low (the only consumable is the inked ribbon). They print perfectly well on paper of very poor quality, which lowers the cost even further. Non-standard paper sizes are possible, which matters for strictly accountable forms made of good-quality paper (for example, a railway ticket from the "Express" automated control system, 2011).
• Printing on unconventional materials. Some printer models (those with a straight paper path) can print on passports, for instance.
• Resistance of the printout to external influences. Very good; printouts withstand water and abrasion. The marks left by the pins also make documents harder to forge. Printouts fade over time, but not critically, and even decades later they remain legible.
• Possible length of the printout. Unlimited. There may be print spooler limitations (as in Windows, for example, where printing is done only in pages). Paper can be fed manually (sheet by sheet) or from a roll.
• Environmental friendliness. Low power consumption, small volume of consumables that are easy to dispose of, and modest paper requirements. Loud noise.
• Ease of maintenance. Works in the most spartan conditions. Before it runs out, the cartridge gives warning by producing low-contrast printouts. As a last resort, carbon paper can be used for printing instead of a cartridge. With roll feed, the paper practically never jams.
• Main present-day application. Printing documents. Dot matrix printers can be found in banks, ticket offices, various agencies, laboratories, medical facilities, and inside cash registers.

Inkjet printers

Epson CX3200 inkjet printer

Printer carriage fitted with Epson DX7 print heads

Carriage drive gearbox of a TechnoJet 160 printer

Material drying fans (Wit-Color400 printer)

The operating principle of inkjet printers is similar to that of dot matrix printers in that the image on the medium is built up from dots. But instead of heads with pins, inkjet printers use an array of nozzles (that is, a head) that prints with liquid colorants. The print head may be built into the ink cartridges (this approach is used mainly in office printers by Hewlett-Packard and Lexmark). Other office printer models use replaceable cartridges while the print head stays in place when a cartridge is changed. In most industrial printers the ink is delivered to the heads mounted in the carriage through an automatic ink supply system.

There are two ways of implementing colorant atomization technically:

• Piezoelectric (Piezoelectric Ink Jet) — a piezoelectric crystal is located above the nozzle. When an electric current is applied to the piezoelectric element, it bends, elongates or pulls on a diaphragm (depending on the type of print head), which creates a local zone of increased pressure near the nozzle; a droplet forms and is then ejected onto the material. In some heads the technology allows the droplet size to be varied.
• Thermal (Thermal Ink Jet) (also called BubbleJet; developed by Canon, the principle having been worked out in the late 1970s) — a microscopic heating element is located in the nozzle, and when an electric current passes through it, it instantly heats up to a temperature of several hundred degrees; the heating forms gas bubbles in the ink (English bubbles — hence the name of the technology), which push droplets of liquid out of the nozzle onto the medium.

The print heads of inkjet printers are built using the following types of colorant delivery:

• Continuous delivery (Continuous Ink Jet) — the colorant is supplied continuously during printing, and whether it reaches the surface being printed is determined by a colorant flow modulator (the patent for this printing method is said to have been granted to William Thomson in 1867). In the technical implementation of such a print head, colorant is fed under pressure into a nozzle and, on leaving the nozzle, breaks up into a train of microdroplets (with a volume of a few tens of picoliters) that are additionally given an electric charge. The colorant stream is broken into droplets by a piezoelectric crystal mounted on the nozzle, on which an acoustic wave (at a frequency of tens of kilohertz) is generated. The droplet stream is deflected by an electrostatic deflection system (a deflector). Those colorant droplets that are not to reach the printed surface are collected in a colorant collector and, as a rule, returned to the main colorant reservoir. The first inkjet printer built using this method of colorant delivery was released by Siemens in 1951.

• Drop-on-demand delivery — colorant is delivered from the print head nozzle only when it actually has to be applied to the area of the printed surface corresponding to that nozzle. It is precisely this method of colorant delivery that has become the most widespread in modern inkjet printers.

Comparison with other types (for photo printers)

• Print quality. High quality (up to 300 lpi — no other printer can boast such sharpness) is achieved only on specially coated paper. On ordinary office paper the edges look "fuzzy". Sharpness on ordinary office paper is also improved by using special pigment inks.
• Color rendering. Colors may be unstable (different batches of ink, ink settling when idle and being stirred up during operation). On the whole, however, because photo printers can have 8 or more colors, color rendering is very good when they are calibrated regularly (coming very close to the industry leader, chemical photographic printing).
• Print speed. On simple personal printers it is comparable to that of a dot matrix printer, about a minute per A4 page. Printing black-and-white documents is usually faster. There are inkjet printer models with print speeds of up to 60 black-and-white pages per minute.
• Cost per page. With original consumables it is very high, more than a dollar per photographic page. Even a black-and-white text page costs several times more than the equivalent laser page. Using third-party inks and paper, however, can cut the cost by a factor of tens.
• Resistance of the printout to external influences. Depends on the ink composition and the print material. With water-soluble inks and plain office paper the printouts are vulnerable to water and may fade. With pigment inks (used in almost all office inkjet printers) light fastness and water resistance are an order of magnitude better. Using photo paper also makes the printout resistant to water and fading.
• Printing on unconventional materials. Inkjet printers (with a suitably designed feed path) can print even on souvenirs with uneven surfaces. No other printer is capable of this. Moreover, the inks can have entirely different physical and chemical properties, so it is possible to print on heat-transfer film or on fashionable ladies' fingernails, for example.
• Possible length of the printout. Theoretically unlimited. There may be print spooler limitations (as in Windows, for example, where printing is done only in pages). Inexpensive office printers may lack a roll paper feed mechanism.
• Environmental friendliness. Low noise. Depending on the chemical composition of the ink, solvent evaporation is possible.
• Ease of maintenance. Extremely temperamental; trouble-free operation is possible only if the printer prints periodically with all of its cartridges. Inexpensive office printers often ran out of ink; continuous ink supply systems (CISS) have largely solved this problem.
• Main present-day application. Photo printing, wide-format printing, and special kinds of printing. In the early 2000s they were widely promoted as personal printers. In the 2010s they are coming back into fashion as personal printers, often black-and-white and with a built-in CISS.

The main characteristic of a printer on which the optical resolution most strongly depends is the type, number and arrangement of the print heads on the carriage.

Photo printers and office printers are rarely equipped with more than one head per color. This is because the requirements for print speed are modest, and in addition the fewer heads there are, the simpler and more effective the system for calibrating and aligning them.

Wide-format and interior printers are equipped with two to four heads per color.

For effective drying and to keep the material from sticking together, inkjet printers are fitted with systems for heating the print field and blowing air over the printed material. In UV printers the ink is cured by radiation from lamp or LED emitters that travel along with the carriage. To reduce burning of the surface of the printed material by UV radiation, the emitters are switched off or covered by opaque shutters while the carriage moves over unprinted areas.

In office printers, in order to reduce the cost of printing and improve certain other printing characteristics, a continuous ink supply system (CISS) is also used, which is something like a "gravity-fed" ink delivery system. The cartridge acts as the damper.

At present, A4 and A3 inkjet printers are being actively displaced by color laser printers. This trend is driven by the considerably lower consumption and lower cost of the consumables used in laser printing, and by the simplicity of servicing color laser printers, which amounts to no more than replacing the toner and the rollers.

The most significant advantage of inkjet printing over laser printing is the length of a continuous printout, limited only by the length of the roll material. In laser printers the length of the printout is limited by the circumference of the intermediate carrier — the roller or the belt. On the largest laser printers the print length can reach a meter. On office inkjet printers, because of the printers' extremely narrow specialization and automation, the low performance of the Print Spooler (Windows), the high cost of programs that replace the Print Spooler, such as FlexiSign, Caldera and the like, and the complete absence of the mechanisms needed for printing on roll media, continuous printing of unlimited length is in most cases impossible to implement.

Dye-sublimation printers

Thermal sublimation is the rapid heating of a colorant in which the liquid phase is skipped. Vapor forms directly from the solid colorant. The smaller the portion, the greater the photographic latitude (dynamic range) of the color rendering. The pigment of each of the primary colors, of which there may be three or four, sits on a separate (or on a shared multilayer) thin polyester ribbon (the dye-sublimation printers of Mitsubishi Electric). The final color is printed in several passes: each ribbon is drawn in turn beneath a firmly pressed thermal head consisting of a multitude of heating elements. As they heat up, they sublimate the colorant. Because the distance between the head and the medium is small, the dots are positioned consistently and come out very small in size.

One of the serious problems of dye-sublimation printing is the sensitivity of the inks used to ultraviolet light. If the image is not covered with a special ultraviolet-blocking layer, the dyes soon fade. When solid dyes and an additional laminating layer with a UV filter are used to protect the image, the resulting prints do not warp and withstand humidity, sunlight and even aggressive environments well, but the cost of the photographs goes up. The full-color capability of the dye-sublimation process has to be paid for with a long printing time for each photograph (printing a single 10×15 cm shot on a Sony DPP-SV77 printer takes about 90 seconds). Manufacturers claim a photographic color depth of 24 bits, which is more wishful than real. In practice the photographic color depth is no more than 18 bits.

The best-known manufacturers of dye-sublimation printers are Canon and Sony.

Comparison with other types (for photo printing)

• Print quality. A good picture with no visible halftone screen (to output a light color, the printer evaporates a smaller amount of dye). In terms of screen ruling they come close to magazine photography.
• Color reproduction. Very good.
• Print speed. About a minute per 10×15 photograph. Professional printers take 6–15 seconds.
• Cost per print. On a consumer printer, 13–15 rubles per print. On a professional one, less than 5 rubles.
• Printing on unconventional materials. Not provided for.
• Resistance of the print to external influences. It is covered with a film after printing. Protected against water and fading.
• Possible print length. Limited to the photograph format only, usually 10×15.
• Environmental friendliness. Low noise.
• Ease of maintenance. More reliable than inkjets; idle periods are no threat to dye-sublimation printers. They are vulnerable to dust.
• Main current application. Photo printing.

Laser printers

HP LaserJet 4100TH laser printer

HP 4000 laser printer. A model from the 1990s.

The technology that was the forerunner of modern laser printing appeared in 1938, when Chester Carlson invented a printing method called electrography, later renamed xerography.

The principle of the technology was as follows. A static charge is distributed evenly over the surface of the photosensitive drum by a charge corotron (or a charge roller), after which a laser diode (in LED printers, an LED array) removes this charge in the required places, thereby placing a latent image on the drum surface. Toner is then applied to the photosensitive drum. The toner is attracted to the discharged areas of the drum surface that hold the latent image. After that the drum rolls across the paper and the toner is transferred to the paper by a transfer corotron (or a transfer roller). The paper then passes through the fusing unit, where the toner is softened and pressed into the structure of the paper, while the photosensitive drum is cleaned of toner residue and discharged in the cleaning unit.

The first laser printer was EARS (Ethernet, Alto, Research character generator, Scanned Laser Output Terminal), invented and built in 1971 at the Xerox Corporation; series production was set up in the second half of the 1970s. The Xerox 9700 printer could be bought at the time for 350 thousand dollars, but it printed at a speed of 120 pages per minute.

To make users pay more, digital counters began to be built into the cartridge or into the printer itself in order to verify the authenticity of the toner and to make refilling impossible.

Comparison with other types

• Print quality. High; in expensive models it approaches offset printing (models with a resolution of 2400 dpi are produced).
• Color reproduction. Toner made on a paraffin base has stable characteristics. Since the printing unit for each color is large and expensive, only four colors in the CMYK scheme are used, and a photographic image comes out with a coarse halftone screen (about 80 lpi), especially in the light tones. Color laser printers make it possible to print high-quality color images, but no models with photographic quality are produced at present.
• Print speed. Modern personal printers work at a speed of 10–20 pages per minute. Office and industrial printers can have speeds above 100 pages per minute. It should be noted that some time passes before the first sheet is output, which is needed to warm up the fusing unit (from a few seconds to tens of seconds). Some personal printers (HP and Canon) use fusing units that require no warm-up.
• Cost per print. The lowest among all types of printers (a few US cents per page for black-and-white printing and tens of cents for color). Personal printers use relatively expensive cartridges (rated for a volume of 1.5 to 3 thousand pages), which seriously increase the cost per print. Refilling cartridges makes it possible to reduce the cost per print, but manufacturers do not provide for refilling as standard (and even create artificial obstacles, for example by fitting memory chips into cartridges). Print quality with refilled cartridges is not guaranteed. Many mid-range and high-end office printers provide for toner refilling as standard, and it is precisely these printers that have the lowest cost per print.
• Printing on unconventional materials. Some types of printers can print on glossy paper, envelopes, labels and transparent film. All materials must be resistant to high temperatures and have a certain structure, weight, thickness and flexibility. All printers are intended to work with standard office paper with a weight of about 80 g/cm². Any other types of material should be used only from the list recommended by the manufacturer.
• Resistance of the print to external influences. They hold color well and are waterproof, but have poor resistance to mechanical impact. For this reason documents issued for long-term use (a passport, for example) are printed either on printers of other types or in a very bold and sharp typeface.
• Possible print length. Laser printing is a continuous process, and the raster image for an individual sheet must be fully prepared in memory before printing begins. For that reason the size of the printing area is usually limited, and the paper feed mechanism is designed to work with stacks of a certain identical format (usually A4 or A3). Wide-format printers are designed to feed paper from rolls (with formats up to A0), with automatic cutting.
• Environmental friendliness. They are practically silent. If the air filters fail, they can pollute the air with ozone and toner. According to current data, toner is hazardous as an inert dust and because of pyrrole (a by-product of carbon black manufacture).
• Ease of maintenance. They work reliably in ordinary home and office conditions. The printer usually "warns" of an imminent cartridge replacement by streaks on the print. That said, toner stains and is hard to wash out, so it is not worth refilling an empty cartridge at home. The photosensitive drum also requires regular replacement (its service life is on the order of 10 thousand pages, but it can be reduced by the use of poor-quality paper or non-original toner and by frequently printing one page per job; in the cheapest printers it is built into the cartridge), as do the paper feed rollers. The printer contains a powerful (up to 1000 W) electric heating element and therefore cannot be run from a UPS.
• Main current application. An indispensable helper in any office. In the 2000s they became so cheap that they also became affordable for home users. Because of their high-quality single-color image, laser printers are used in the printing industry for phototypesetting.

Thermal printers

The printing process consists in forming the image with a thermal print head on special heat-sensitive paper, which turns black where it is heated, forming characters. They are simple and cheap and require no colorant, but the print quality is low.

Comparison with other types

• Print quality. Reaches 300 dots per inch.
• Color reproduction. Black-and-white only.
• Print speed. Very fast, faster than dot matrix and inkjet printers.
• Cost per print. Extremely low: 1 m² of receipt tape costs roughly twice as much as 1 m² of office paper. That is cheaper than laser prints.
• Printing on unconventional materials. They print only on thermal paper. Films and self-adhesive labels with a thermal coating are also produced.
• Resistance of the print to external influences. The prints are not resistant to friction or pressure; they fade within a few years. The prints withstand heating to the temperature of a human hand (36.6°), but do not always survive exposure to household heating appliances. For example, if a product with a label printed on a thermal printer is heated in a microwave oven, the label turns black and becomes practically illegible. Besides that, the label can blacken on contact with certain household cleaning agents.
• Possible print length. Limited only by the software.
• Environmental friendliness. The thermal print head makes no noise; the noise of a working printer is limited to that of the material feed mechanism. There is practically no pollution. That said, thermal paper contains the harmful substance bisphenol A.
• Ease of maintenance. Extremely reliable; the only consumable is thermal paper.
• Main current application. They are widely used in small-format and compact printing devices: fax machines, cash registers, ATMs and service terminals.

3D printer (digital additive manufacturing device, prototyping device)

A 3D printer is equipment intended for reproducing digital data (a 3D model) in the form of a solid model of an object, a finished part or a product. The object is reproduced layer by layer, by creating and integrating individual cross sections.

Technologies for reproducing three-dimensional objects (additive technologies) are the opposite of 3D milling (subtractive technologies). The key difference is that with subtractive technology everything superfluous is removed from the workpiece, whereas with additive technology the reverse process takes place: the body of the object is built up.

A comparison table of the advantages and disadvantages of these technologies:

3D inkjet modeling devices

An inkjet modeling device is very similar in design to an ordinary inkjet printer. The key difference is a mechanism that deposits a polymerizable or hardening material layer by layer onto the surface of each working layer. During operation, a polymerizable or hardening material is applied to every newly formed layer. After each layer has been deposited, the inkjet print head applies a polymerizing additive or another hardening activator in those areas where the polymerizable or hardening material is meant to set. The cycle repeats until the solid body is fully formed inside the mass of unpolymerized powder material. Gypsum is often used as the working material, since it hardens on contact with ordinary, inexpensive water-based inkjet inks.

Laser 3D modeling devices

While a laser 3D modeling device operates, liquid photopolymer is deposited layer by layer onto the build platform. After each layer has been deposited, the surface of the photopolymer is exposed to a laser beam in those places where the photopolymer is meant to cure. The object is thus built up layer by layer. Once the last layer has been formed, the hardened object simply has to be lifted out of the liquid photopolymer.

There are also laser 3D modeling devices that use metal or polymer powder instead of photopolymer; as each new layer is formed, the powder is sintered to a solid state by the laser. Laser sintering technologies may differ in the type and power of the laser emitter used.

3D modeling devices based on plastic extrusion

In such devices, molten polymer is deposited onto the future part by continuous extrusion as a filament ranging from a few tenths of a millimeter to several millimeters in diameter . Bonding to one another, the layers form the future part. The motion of the extruder is controlled by a three-axis kinematic system similar to the one used in pen or cutting plotters and in engraving and milling machines. Special extruder attachments for an ordinary CNC milling machine are also known, converting it into a 3D modeling device.

3D printers for printing on three-dimensional objects (on 3D objects)

Unlike traditional printers, which create an image on flat media in one way or another - on paper, film or metal foil - 3D printers can apply an image to three-dimensional (volumetric) objects, for example mugs, mobile phones, souvenirs, key fobs, pens and other entirely ordinary items.

Unlike pad printing, a 3D printer requires no printing plates or color registration and can print quickly, including in full color, in arbitrarily small runs.

The operation of 3D printers is generally based on inkjet printing, as in inkjet printers, except that the paper feed mechanism is replaced by a device that orients the object being printed during printing.

There are also 3D printers that perform full-color printing on finger or toe nails, which is used successfully in the form of manicure known as nail art.

Other printers

• Drum printers (English drum printer).

The first printer, named UNIPRINTER, was built in 1953 by Remington Rand for the UNIVAC computer. The main element of such a printer was a rotating drum with raised images of letters and digits on its surface. The width of the drum matched the width of the paper, and the number of rings carrying the alphabet was equal to the maximum number of characters in a line. Behind the paper was a row of hammers driven by electromagnets. At the moment the required character on the rotating drum passed by, the hammer struck the paper, pressing it against the drum through an inked ribbon. A whole line could thus be printed in one revolution of the drum. The paper was then advanced by one line and the machine went on printing. In the USSR such machines were called alphanumeric printing devices (ATsPU). Their printouts can be recognized by a typeface resembling that of a typewriter and by letters that "jump" along the line. The output speed of the drum printer was and remains the highest among all known printing devices, and even that was far from the limit of what the technology could do. Printing was done on roll paper, which is why system programrs called the resulting printout a "bedsheet".

• Daisy wheel printers (petal printers)

In principle of operation they were a hybrid of the drum printer and the typewriter. They had a single set of letters, arranged on the flexible petals of a plastic disc. The disc rotated, and a special electromagnet pressed the required petal against the inked ribbon and the paper. Since there was only one set of characters, the print head had to be moved along the line, and the printing speed was noticeably lower than that of drum printers. By replacing the character disc one could obtain a different typeface, and by inserting a ribbon of a color other than black one could obtain a "color" printout. For this purpose the printer's command set could include a "pause" command.

Besides the daisy wheel, the part carrying the type could take the form of a thimble, a (truncated) sphere or even a caterpillar chain (chain printer).

• Teletype printers consisted of an electromechanical part replicating an electric typewriter, and a modem. That is, an electric keyboard, an electromechanical lever-type character printer and a device for receiving and transmitting information over a communication channel were combined in a single unit. A punched tape writing and reading device, usually 5-track (5-bit), was connected in addition.

• Experimental developments:
  • As part of an environmental protection program, the Japanese company PrePeat released a printer that needs neither ink, nor toner, nor paper to operate. Thin white plastic is used for printing instead of paper. The same sheet can be used many times: before it is printed on again, it is erased automatically inside the printer.
• the hot wire cutter type of printer

A hot wire cutter is a simple tool that allows shapes of various forms to be cut quickly out of expanded polystyrene. It can be used as an alternative to a 3D printer for rapid prototyping, or as a tool for producing finished parts. For example, hot wire cutters are partly used in aeromodeling.

A hot wire cutter consists of a taut metal wire heated by an electric current, which allows it to melt expanded polystyrene on contact. By moving the wire relative to the block of expanded polystyrene, one can control the final shape of the item, but in one way or another it will be made up of ruled surfaces, so this tool cannot be used to create concave surfaces, and creating convex ones often requires many cuts.

The robot's control algorithm takes the desired shape of the item and computes the motion paths of both manipulators for it. The paths consist of a set of discrete curves which, once interpolated, yield a single cut surface. For each cut the algorithm computes a set of curves such that the cut reduces the difference between the surface of the item's model and the cut surface as much as possible. At each subsequent step it computes the current deviation from the ideal shape and creates a new set of curves to minimize it.

Plotters , graph plotter , plotter

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Plotters , graph plotter , plotter ( English Plotter ) - a device intended for outputting data in graphical form onto paper.

Most often this is a wide-format inkjet printer designed to print in the Cartesian coordinate system on sheets of A0, A1, A2, A3, A4 and other formats of various thicknesses (from 80 g/m², whatman paper, semi-whatman paper and so on). It is used for printing, in both black-and-white and color versions, drawings, diagrams, maps, advertising posters and large-format price tags (for example in supermarket windows).

Features: large ink reservoirs, the option of connecting a CISS (continuous ink supply system) for even larger print volumes, "hot" replacement of ink reservoirs and of the cartridge .

It can also be equipped with a head carrying a blade, or with a special pen, in which case the output is produced by cutting material along curved lines (on Oracal vinyl, heat transfer films and so on). Data is sent to the plotter from programs intended for working with vector graphics (Corel Draw, Adobe Illustrator and so on)

Most often it is used for advertising purposes to create banners, billboards and lettering.

Internet printers

Recently, printers have appeared on the office equipment market whose software supports a direct connection to the Internet (usually through a router), which allows such a printer to operate independently of a computer. Such a connection provides a number of additional capabilities:

• printing documents or web pages straight from the printer's display;
• printing documents or web pages from any web-enabled device (including a remote one) without having to install a printer driver on it;
• viewing the printer's status and managing print jobs using any browser, regardless of location;
• prompt automatic updating of the printer's software.

History and operating principles of printers

The era of home printers began in 1985, when the LaserJet from Hewlett-Packard and the LaserWriter from Apple Computer appeared on the market.

In 1981 thermal inkjet printing technology was presented at the Canon Grand Fair exhibition. In 1985 the first commercial model of such a monochrome printer appeared - the Canon BJ-80; in 1988 the first color printer appeared - the BJC-440, in A2 format with a resolution of 400 dpi.

Printer design

Printer cartridge

The colorant (ink, toner) used in a printer is usually held in cartridges.

Printer manufacturers recommend refilling their printers with ink/toner of their own manufacture; technically, however, it is difficult to prevent the use of ink/toner from third-party manufacturers (just as it is difficult to build a car that runs only on fuel from the car's manufacturer). Buying so-called genuine cartridges costs more than refilling cartridges with ink or toner from third-party manufacturers.

There is an entire industry of ink manufacturers who supply ink to printer manufacturers under OEM agreements, and also directly to users under their own brand, for example inktec, ink-mate. Current Canon printer models use Fine cartridges with a built-in chip that monitors ink delivery and the ink level. But this does not prevent such cartridges from being refilled, even without reprogramming the chip: if the "ink is out" information remains after refilling, the printer does not refuse to print, it merely reports the refill.

Cartridges can be refilled repeatedly, provided certain requirements are met (either compatible ink is needed, or the cartridge and the head must be flushed, in the case of inkjet printers).

Besides the cartridge refill system, inkjet printers also have a system that supplies ink from an external reservoir (the so-called CISS).

Print head of an inkjet printer

A Xaar382 head (after two years of service)

Teardown of a Xaar 382 head

Spectra-128 "SkyWalker" print head

Spectra-128 "SkyWalker" print head (cut open)

Definition:

• A print head is the part of a printer that applies ink to the surface of the material being printed on.

The print head is a very expensive printer component; some types of print heads used in wide-format printers cost as much as 100,000 rubles (for certain Spectra heads) and more. Beyond that, the print head is in most cases a consumable - a very expensive consumable that can easily be damaged through careless handling. Reliable, stable print head operation requires ink of proper quality; the ink storage conditions must also be observed (some kinds of ink must not be allowed to freeze or overheat). Ink shelf life must be respected (do not use expired ink). The printing surface of the heads must be protected from snagging on the material and from scratches. Timely replacement of the ink filters noticeably slows the rate at which heads clog.

Classification:

• Thermal print heads. Used mainly in office inkjet printers, and in Chinese aqueous-pigment interior printers based on the Kodak Encad. They are simple, inexpensive and not very reliable.
• Piezoelectric print heads. Used in office inkjet printers and in most types of industrial inkjet printers.

Classification of piezoelectric print heads:

• Heads for printing with aqueous and aqueous-pigment inks.
• Heads for solvent printing. Used for printing with solvent-based inks and other aggressive solvents. The body and all parts of heads intended for solvent printing are made as resistant as possible to chemically aggressive substances.
• Heads for UV printing. Unlike heads intended for solvent printing only, these in most cases have a built-in ink pre-heating module (UV ink is much thicker than solvent ink, but thins out readily when heated). UV heads are equipped with two inlets for feeding ink into the ink chamber and for flushing the ink chamber straight through in case solid ink sediment settles out (UV printing often uses white ink containing a zinc pigment (zinc oxide) or a titanium pigment (titanium(IV) oxide), whose distinctive feature is a tendency to form sediment).

Conditions for high-quality print head operation:

• During printing there must be no ink drops on the outer surface of the print head, because the drops can cover some of the nozzles, and instead of spraying onto the material those nozzles will simply hammer away into the drop.
• There must be no air bubbles in the ink chamber of the print head. Like any liquid pump, the head cannot pump air effectively, and air bubbles that get into the nozzles stall there and are not pumped out any further.
• The pressure at the print head inlet must be negative and slight. With excessive negative pressure the head sucks in air (backwards, through the nozzles). With even the slightest positive ink pressure, drops immediately form on the head.
• The print head must be close enough to the material being printed for the scatter of the ink drops to be negligible.
• The voltage on the print head's piezo elements must be high enough for the drops to have sufficient mass and velocity, so that the scatter angle of the drops is minimal.
• The voltage on the piezo elements must not exceed the value at which excessively abrupt actuation of the piezo elements produces cavitation in the head's ink chamber (the ink literally boils, filling the head with air).
• There must be no lint or dust particles on the surface of the print head. Dust can partly cover the nozzles; ink sprayed into the dust will accumulate on the surface of the print head and periodically drip onto the material. In addition, a fiber (hair) stuck to the head can drag across ink that has not yet dried, leaving dirty streaks.

Ink pump of an inkjet printer

Peristaltic ink pump of a printer

Teardown of a printer's peristaltic ink pump

Definition:

• An ink pump is the part of a printer that pumps ink.

Ink pumps are used both in various ink supply systems and in systems for automatic cleaning of the print head (heads).

A pump working in an ink supply system operates together with an ink level sensor located in the sub-tank - the reservoir from which the print head is fed. The pump switch-on sequence: the printer prints - the print head consumes ink from the sub-tank - the ink level in the sub-tank drops - the level sensor trips - the pump switches on and pumps ink from the main reservoir (the ink canister) into the sub-tank. The pump switch-off sequence: the running pump has filled the sub-tank with ink - the level sensor switches off - the pump switches off. The sensor signal is fed either directly to the pump or through intermediate electronic devices that perform all sorts of auxiliary functions: amplifying the level sensor signal, monitoring the ink level in the source reservoir, switching the pump off if the sensor sticks, counting ink consumption, regulating the pump's rotation speed, and so on.

A pump used in an automatic print head cleaning system operates together with a sealed cap that is pressed against the bottom surface of the print head for the duration of the cleaning. The pump draws ink and air out of the cap, creating negative pressure inside it. Under the action of that negative pressure, ink begins to flow from the print head nozzles into the cap. In this way the head is cleaned, dried-out nozzles are cleared, and air is removed from the print head's ink chamber.

Ink pumps are characterized by:

• maximum pressure
• ink pumping rate
• range of operating voltages
• power consumption
• resistance of the pump's construction to chemical attack by various types of ink.

Ink pumps are quite easy to repair. The main cause of pump failure is contamination of the pumping mechanisms, which can easily be cleaned out.

Carriage drive of an inkjet printer

The carriage drive of an inkjet printer is the set of mechanisms that moves the carriage of an inkjet printer.

The carriage drive of an inkjet printer consists of:

• Mechanisms attaching the carriage to the beam, which allow the carriage to move freely along the axis of the beam while remaining rigid under loads applied in other directions. A typical inkjet printer carriage is attached to the beam by a linear rail and a linear bearing (bearings); on some printers (for example, older Mimaki JV2 models) two round guide rods are used instead of a single rail. Office inkjet printers mount the carriage on rollers, or on two round guides, or on a combination of rollers and a single round guide. Linear rail guides are not used in office printers because of the high cost of this type of mounting (the price of a rail linear bearing alone can be several times the average cost of a desktop printer). The carriage may also be mounted on a linear motor.
• The carriage drive belt. On some printers a flexible steel band may be found instead of a toothed belt. The band has no teeth to create vibration as it engages the drive gears and provides smoother carriage motion, but compared with a belt it has a shorter service life, and there is no way to track how much of that life is left, because unlike a belt the band does not begin to crumble before breaking - it snaps all at once. On some printers the carriage is driven by a steel cable wound onto a two-section spool.
• The carriage drive motor. A servo motor with feedback is usually used. Office printers often use ordinary stepper motors.

features of software-side printing

Print buffering - creating a print queue; it lets the computer's processor speed up processing of a print job by temporarily saving it on the hard disk before sending it to the printer. As a result, the processor can return control to the program that is printing much faster than if the program itself had to process the whole job and send it directly to the printer.

spool (English) - to read in/write out data;
• SPOOL - short for Simultaneous Print Operations On Line - simultaneous online processing of print jobs;
• spooler (print spooler) - spooler, print spooler - 1) the print queue manager - a scheduler program that accepts documents sent to print by the user, stores them (on disk or in main memory) and sends them in queue order to the selected printer. The disk location of the print queue manager (Spooler SubSystem App) is \Windows\System32\spoolsv.exe; 2) the print subsystem receives, processes, schedules and distributes documents sent to print. The disk location of the print subsystem (Spooler SubSystem DLL) is \Windows\System32\spoolss.dll;
• spool file - spool file - the file into which the contents of a print job are dumped during spooling;
• spooling - 1) spooling (the process of handling documents sent to print, which are stored on disk or in RAM until the printing device is able to process them); 2) reading in (data); writing out (data) (concurrently with executing a task);
• print spooling - sending a job to print with (preliminary) spooling;
• print queue - the queue of print jobs (print queue) - the list of documents waiting to be printed. The print queue (Windows Vista and XP) is built in the folder \Windows\system32\spool\PRINTERS;

Unconventional uses

• Even before dot matrix (graphics-capable) printers appeared, people wanted to print at least something resembling graphics. This could be done even on a drum printer or another character printer by means of so-called ASCII art. Even today some applications (the GIMP image editor, for example) offer an option to output an image as an ASCII text file suitable for printing on a character printer.

• Electronics hobbyists successfully use laser printers in the "toner transfer" (laser-and-iron) method of making printed circuit boards, to create the etch mask.[12]In the same way, lettering or images, including color ones, can be applied to the housings of electronic equipment and other three-dimensional objects that will not fit into a printer in the normal way. To do this, mirror-reversed text is printed on waxed paper and transferred onto the object while hot, under pressure.

• Laser printers can be used to create lettering and images on metal surfaces. For this a special toner is loaded into the cartridge and a mirror image or mirror-reversed text is printed. The printed sheet is then placed on a metal plate under a heat press. Under pressure and at high temperature the toner reacts chemically with the metal, forming stable compounds. This technology is called "Grawerton".

Interesting facts

• Many printers leave yellow dots on the printed sheets.
• some printers add a hidden digital signature or identifier to the image
• some printers and copiers produce a black image when copying world currencies

See also

• Virtual printer
• Wide-format printer
• Copier
• Multifunction device (MFP)

• [[b3292]]

• [[b2042]]

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See also

• 3.3.1 STRUCTURAL SCHEME OF MATTIC PRINTER AND ITS FEATURES. TROUBLESHOOTING AND REPAIRING THE MATRIX PRINTER
• The evolution of printing devices, printers, plotters, 3d printers
• 3.3.3. STRUCTURAL SCHEME OF LASER PRINTER AND ITS FEATURES. DIAGNOSTICS OF LASER PRINTER FAULTS
• Printers and MFPs: Types, Classification and Features