Laser printer wiki. How they “printed” before the advent of printers
The history of laser printers began in 1938 with the development of dry ink printing technology. Chester Carlson, working on the invention of a new way to transfer images to paper, used static electricity. The method was called electrography and was first used by the Xerox corporation, which released the Model A copier in 1949. However, for this mechanism to work, certain operations had to be performed manually. Ten years later, the fully automatic Xerox 914 was created, which is considered the prototype of modern laser printers.
The idea of "drawing" what would later be printed directly onto the copy drum with a laser beam came from Gary Starkweather. Since 1969, the company has been developing and in 1977 released the Xerox 9700 serial laser printer, which printed at a speed of 120 pages per minute.
The device was very large, expensive, and intended exclusively for enterprises and institutions. And the first desktop printer was developed by Canon in 1982, a year later - the new model LBP-CX. HP, as a result of cooperation with Canon, began production of the Laser Jet series in 1984 and immediately took a leading position in the market of laser printers for home use.
Currently, monochrome and color printing devices are produced by many corporations. Each of them uses its own technologies, which can vary significantly, but the general principle of operation of a laser printer is typical for all devices, and the printing process can be divided into five main stages.
The print drum (Optical Photoconductor, OPC) is a metal cylinder coated with a photosensitive semiconductor on which an image is formed for subsequent printing. Initially, the OPC is supplied with a charge (positive or negative). This can be done in one of two ways using:
- corotron (Corona Wire), or coronator;
- charge roller (Primary Charge Roller, PCR), or charging shaft.
A corotron is a block of wire and a metal frame around it.
Corona wire is a tungsten filament coated with carbon, gold or platinum. Under the influence of high voltage, a discharge occurs between the wire and the frame, a luminous ionized area (corona), an electric field is created that transfers a static charge to the photodrum.
Usually a mechanism is built into the unit that cleans the wire, since its contamination greatly impairs the print quality. Using a corotron has certain disadvantages: scratches, accumulation of dust, toner particles on the filament or its bending can lead to an increase in the electric field in this place, a sharp decrease in the quality of printouts, and possibly damage to the surface of the drum.
In the second option, a flexible film made of special heat-resistant plastic wraps the supporting structure with a heating element inside. The technology is considered less reliable and is used in printers for small businesses and home use, where heavy equipment loads are not expected. To prevent the sheet from sticking to the stove and twisting it around the shaft, a strip with paper separators is provided.
Color print
Four primary colors are used to form a color image:
- black,
- yellow,
- purple,
- blue.
Printing is carried out on the same principle as black and white, but first the printer splits the image that needs to be obtained into monochrome images for each color. During operation, color cartridges transfer their designs onto paper, and their superimposition on each other gives the final result. There are two color printing technologies.
Multipass
This method uses an intermediate carrier - a roller or toner transfer ribbon. In one revolution, one of the colors is applied to the tape, then another cartridge is fed to the desired location and the second is superimposed on top of the first image. In four passes, a complete image is formed on the intermediate medium and transferred to paper. The printing speed of color images in printers using this technology is four times slower than monochrome.
Single pass
The printer includes a complex of four separate printing mechanisms under common control. The color and black cartridges are lined up, each with a separate laser unit and transfer roller, and the paper runs under the drums, sequentially collecting all four monochrome images. Only after this does the sheet go into the oven, where the toner is fixed on the paper.
Have fun typing.
Laser printer(laser printer) is one of the types of computer printers that allows you to quickly produce high-quality prints of text and graphics on plain paper. Like photocopiers, laser printers use a xerographic printing process, but the difference is that the image is formed by directly scanning the photosensitive elements of the printer with a laser beam.
Laser printer device.
Any modern printing device consists of three main components: printing mechanism(the word “mechanism” when applied to a laser printer, generally speaking, is not entirely appropriate; in fact, it is a very precise and complex electronic-optical-mechanical device, many of whose elements, especially the toner, implement the latest achievements of chemical technologies), controller, containing a raster processor that converts data received from the computer into graphic images of printed pages (in some cases, this task can also be assigned to the PC’s central processor), and interface block, providing bidirectional data exchange with a computer.
Printing mechanism
Center of the laser printer printing mechanism: -photo drum, sometimes also called a photo shaft,
-metal tube, coated with a film of organic photosensitive semiconductor (ORC, Organic Photo-Conductor).
The resistance of the photosensitive layer in the dark is very high, but when illuminated it decreases significantly. It is he who, with the help of toner, transforms it into visible and transfers to paper the invisible image formed on it by a laser beam, which is a “map” of electrical charges.
Let's look at the design of the scanner. A modulated beam of an IR laser diode with a power ranging from units (in entry-level printers) to tens (in high-performance printers) of milliwatts, passing a collimator, through a cylindrical lens that changes the elliptical cross-section of the beam to a circular one, hits a high-speed rotating mirror (in the form of a multifaceted prism, usually 10-sided), each face of which deflects the beam over the entire width of the drum. This invisible image now needs to be made visible, and this is where the developer block comes into play.
The development unit consists of a toner hopper, a magnetic roller and a so-called doctor blade. The magnetic roller, located a short distance from the photoconductor or, depending on the specific design, in direct contact with it, captures the toner, which contains magnetic particles (usually iron), and gives it a positive charge. The dosing scraper removes excess toner from the magnetic roller. By adjusting the distance between the scraper and the roller, you can change the amount of toner supplied, and, consequently, the saturation of the resulting image. Fixing is done by squeezing a sheet of toner between two rollers of a fuser, or “fuser” in common parlance. The upper roller heats up to a high temperature (100-300C, depending on the toner material) and melts the toner particles, and thanks to the pressure provided by the lower (pressure) roller, the molten toner penetrates the paper structure, forming a durable image. Toner particles remaining on the drum are cleaned off with a polyurethane wiper blade and sent to the waste bin. To prevent scraped toner particles from getting onto the paper, another mylar scraper is used to guide them into the container. Cleaning the drum is necessary to prevent “ghost” images from appearing on the page, created by toner particles remaining from the previous pass.
Toner powder under a microscope.
Controller
The laser printer controller includes a central processor, random access memory in which bitmap images of printed pages are placed, permanent (usually rewritable) memory in which the controller's firmware is stored, as well as built-in fonts. For network models, starting with mid- and large-workgroup printers, it is almost mandatory to have a built-in interpreter for Adobe's PostScript page description language. This device-independent language has maximum flexibility and allows you to describe the most complex, graphics-rich pages. The current, third, version of the language contains all the tools for describing the most complex color images.
Interface
Until the recent widespread adoption of the USB interface, almost every printer produced in the world, with the exception of rare models with RS-323C or SCSI interfaces, was equipped with a Centronics parallel interface with a 36-pin connector, which was connected by cable to the 25-pin D-shaped connector of the PC LPT port . Initially, the interface had a transfer rate of 150 kB/s and was unidirectional, meaning data could only be transferred from the computer to the printer. Therefore, the computer could not obtain information about the printer status. Subsequently, the interface specification was expanded with EPP (Enchanced Parallel Port) and ECP (Extended Capability Port) modes, using which it was possible to provide bidirectional data transfer and increase the transfer speed to 2 MB/s. The standard describing such a parallel interface was adopted by IEEE in 1994 and was called IEEE 1284. In modern printers, IEEE 1284 is becoming less and less common, and, as a rule, only as an addition to the main USB interface. Version 1.1 of the latter provides bidirectional serial data transfer at (theoretical) speeds of up to 12 Mbit/s (1.2 MB/s), and version 2.0 up to 480 Mbit/s (48 MB/s). Most of the latest printer models are equipped with a USB 2.0 interface, although its maximum transfer speed is often excessive for these purposes. After USB, the most common printer interface now is Ethernet 10/100 Mbit/s. Recently, not only high-performance printers for medium and large workgroups, but also models for small workgroups and even some SOHO-level models have often begun to be equipped with a network interface. Often the printer is standardly equipped with only a USB interface, but it has a slot for installing an optional network interface card, and this can be not only a wired Ethernet adapter, but also a Wi-Fi, Bluetooth, or combined card. For some printer models, an optional IR receiver is available that allows you to print data via the IR port of a laptop or PDA. A modern printer network interface is not just an Ethernet controller. This is actually a print server that implements various protocol stacks, including TCP/IP, IPX/SPX, AppleTalk, NetBEUI, etc. Often, the firmware of a network adapter includes a full-featured HTTP server with a Web site that provides printer management and control its status using a regular browser. The built-in FTP server allows you to transfer jobs to the printer via FTP, as well as upgrade the firmware by transferring new firmware images via FTP. The telnet, time, SMTP, POP3 protocols can also be implemented (in this case, the printer is capable of accepting print jobs and sending messages about changes in its status via e-mail), as well as SSL protection of transmitted data. Some printer manufacturers and a number of independent companies produce external print servers that have, on the one hand, a conventional wired and/or wireless network interface (this can also be a Bluetooth interface), and on the other, one or more (in this case, one The print server can connect several printers) via USB or IEEE 1284 interfaces.
General design of laser printer toner cartridge
A toner cartridge or simply a cartridge is one of the main components of a laser printer, responsible for transferring the generated image onto paper.
Cartridge is a complex electro-mechanical device consisting of dozens of parts. Conventionally, the cartridge can be divided into:
Photosensitive drum (photodrum, OPC - Organic Photo Conductor)
Cleaning blade
Primary charge shaft
Magnetic shaft
Dosing blade
Felt seals
And a number of other details.
The main structural elements of the waste toner compartment (Fig. 2):
Toner is a powder with special properties that is transferred using the electrographic principle to a photodrum pre-charged in a special way and forms a visible image on it, which is then transferred to paper. It can be black, red, blue or yellow. There are different types of toner: chemical, mechanical, etc. At its core, a toner under a microscope is granules of wax or a similar polymer coated with metal oxide (metals) and pigments.
The toner cartridge body is made of high-strength plastic.
Image drum(OPC - Organic Photo Conductor) is an aluminum cylinder on which a photosensitive layer is applied. The photolayer has a different structure and sensitivity, depending on the printer model and cartridge. In addition, photodrums differ in size and gears that ensure its rotation. Photodrums are manufactured for a specific type of cartridge and in most cases it is not possible to use the same photodrums in different cartridges. Let us briefly recall the principle of operation of the cartridge: A laser (in OKI - an LED line), focused on the drum, illuminates the areas onto which the magnetic roll will subsequently apply toner. After the image is formed on the image drum, it is transferred to paper. The photolayer that covers the photodrum is not resistant to mechanical damage and contamination. Using poor quality and/or dirty paper can cause serious damage to the image drum. Therefore, the cartridge must be stored in its packaging. After 2-4 refills, and sometimes even earlier, the photo layer on the photo drum is erased, and the cartridge begins to produce low-quality prints. Replacing the photodrum or “Restoring” is the next stage in the life cycle of the cartridge after refilling. Since the photodrum is the basis for image formation, the print quality greatly depends on its condition. It is impossible to achieve high print quality if the image drum is damaged.
Primary charge shaft(PCR - Primary Charge Roller) is a metal axle enclosed in a rubber shell. PCRs have different rubber layer structures. The main task of this part is to charge the photodrum with a uniform negative charge. In some PCR cartridges, it also serves to clean the photodrum from toner residues and paper dust. PCR also removes any residual charge left on the drum from a previous charge. PCR has a long service life and rarely fails. But damage to this part may degrade print quality. The primary charge shaft is subject to heavy contamination with paper dust and therefore requires regular and thorough cleaning.
Magnetic shaft(Mag Roller) is a roller that transfers toner from the hopper to the drum. Magnetic shafts have different structures. In cartridges produced by HP and Canon, the magnetic roller is a complex structure in the form of a metal roller, the surface of which is coated with a special layer. In Samsung cartridges, the magnetic shaft (sometimes called the developer shaft) is made of high-quality rubber. The magnetic roller plays a significant role in image formation. A damaged magnetic roller will cause significant deterioration in print quality. The magnetic roller is subject to wear, especially in HP and Canon cartridges. The quality of the toner used affects the life of this part. The main defects of this part are scratches and dirt on its shell.
Cleaning blade or squeegee(Wiper Blade) is a special plate that is used to clean the drum of residual toner that was not applied to the paper during the image transfer process. The squeegee is made of durable and elastic polyurethane. The squeegee should fit tightly to the photodrum and at the same time should not damage it. The surface quality of the squeegee blade, the sharpness of the edges and the exact dimensions are very important for the normal operation of the cartridge. The service life of the photodrum depends on the condition of the squeegee, since the squeegee has direct contact with the photodrum during printing. A damaged squeegee will result in unsatisfactory print quality. The main defects of a squeegee are bents, scratches and jagged surfaces. The squeegee is usually changed along with the photodrum. Waste-free cartridges (Lexmark, Samsung, Xerox, etc.) do not have a squeegee as such. A small amount of toner that was not transferred to the paper from the drum during printing is collected by the primary charge roller, the residual toner from which, in turn, is removed by a special dust collector brush.
Dosing blade(Doctor Blade) controls the amount of toner that is applied to the magnetic roller. Dispensing blades have a variety of designs and are made from different materials - polyurethane (Canon, HP, etc.), metal (Xerox, Samsung, Brother, etc.). To ensure even distribution of toner on the magnetic roller, the dispensing blade must have a high quality surface (without concavities or nicks). A damaged dispensing blade will not apply toner evenly across the magnetic roller, resulting in uneven transfer of toner to the image drum and ultimately significantly degraded print quality. In cartridges produced by HP and Canon, the dispensing blades are subject to little wear and tear due to the use of low-quality toner. The dispensing blades in the cartridges of almost all models of Samsung printers and budget Xerox printers are subject to significant wear and require regular replacement. In addition to mechanical wear, the dosing blades are susceptible to contamination and therefore require regular and thorough cleaning or replacement.
Felt seals(Felt Shet) of the magnetic shaft, squeegee and other cartridge components serve to seal the cracks that exist at the junction of various parts. The main task of felt seals is to seal the toner hoppers and the cartridge as a whole. There are many places in a toner cartridge that need sealing, so felt seals come in different types and vary in size and shape. The magnetic roller felt seals are the seat of the magnetic roller and are installed between the toner hopper and the magnetic roller. They fit tightly to the ends of the magnetic roller and prevent toner from leaking out. Felt squeegee seals prevent toner from leaking out from the working surface of the squeegee, and also prevent toner from spilling out of the waste toner bin. Worn felt seals lead to toner spillage in the printer, which leads to contamination of the printer and sometimes even to printer failure. In addition, by allowing toner to leak onto cartridge parts, felt seals can reduce the service life of some cartridge parts.
The main structural elements of the toner compartment (see Fig. 3):
1 Magnetic shaft(Magnetic Developer Roller, Mag Roller, Developer Roller). It is a metal tube, inside of which there is a stationary magnetic core. The toner is attracted to the magnetic roller, which, before being supplied to the drum, acquires a negative charge under the influence of direct or alternating voltage.
2 “Doctor”(Doctor Blade, Metering Blade). Provides uniform distribution of a thin layer of toner on the magnetic roller. Structurally, it is made in the form of a metal frame (stamping) with a flexible plate (blade) at the end.
3 Magnetic shaft sealing blade(Mag Roller Sealing Blade). A thin plate similar in function to the Recovery Blade. Covers the area between the magnetic roller and the toner supply compartment. The Mag Roller Sealing Blade allows toner remaining on the magnetic roller to flow into the compartment, preventing toner from leaking backwards.
4 Toner box(Toner Reservoir). Inside it is the “working” toner, which will be transferred to the paper during the printing process. In addition, a toner activator (Toner Agitator Bar) is built into the hopper - a wire frame designed for mixing toner.
5 Seal, receipt(Seal). In a new (or regenerated) cartridge, the toner hopper is sealed with a special seal that prevents toner from spilling during transportation of the cartridge. This seal is removed before use.
Laser printing principle
In Fig. Figure 4 shows a sectional view of the cartridge. When the printer turns on, all components of the cartridge begin to move: the cartridge is prepared for printing. This process is similar to the printing process, but the laser beam is not turned on. Then the movement of the cartridge components stops - the printer goes into the Ready state.
After sending a document for printing, the following processes occur in the laser printer cartridge:
Charging the drum(Fig. 5). The Primary Charge Roller (PCR) uniformly transfers a negative charge to the surface of the rotating drum.
Exhibition(Fig. 6). The negatively charged surface of the drum is exposed to the laser beam only in those places where the toner will be applied. When exposed to light, the photosensitive surface of the drum partially loses its negative charge. Thus, the laser exposes a latent image to the drum in the form of dots with a weakened negative charge.
Applying toner(Fig. 7). At this stage, the latent image on the drum is converted into a visible image with the help of toner, which will be transferred to paper. The toner located near the magnetic roller is attracted to its surface under the influence of the field of the permanent magnet from which the core of the roller is made. When the magnetic shaft rotates, the toner passes through a narrow gap formed by the “doctor” and the shaft. As a result, it acquires a negative charge and sticks to those areas of the drum that were exposed. “Doctor” ensures uniform application of toner on the magnetic roller.
Transferring toner to paper(Fig. 8). Continuing to rotate, the drum with the developed image comes into contact with the paper. On the reverse side, the paper is pressed against the Transfer Roller, which carries a positive charge. As a result, negatively charged toner particles are attracted to the paper, which produces an image “sprinkled” with toner.
Pin an image(Fig. 9]. A sheet of paper with a loose image is moved to a fixing mechanism, which consists of two contacting shafts, between which the paper is pulled. The Lower Pressure Roller presses it against the Upper Fuser Roller. The upper roller is heated, and upon contact with it, the toner particles melt and adhere to the paper.
Cleaning the drum(Fig. 10). Some toner does not transfer to the paper and remains on the drum, so it needs to be cleaned. This function is performed by the “viper”. All toner remaining on the drum is removed by a wiper into the waste toner bin. At the same time, the Recovery Blade covers the area between the drum and the hopper, preventing toner from spilling onto the paper.
“Erasing” an image. At this stage, the latent image created by the laser beam is “erased” from the surface of the drum. Using the primary charge shaft, the surface of the photodrum is evenly “covered” with a negative charge, which is restored in those places where it was partially removed under the influence of light.
Understanding the principle of laser printing will be useful not only in the process of printing documents, but also in troubleshooting and preventing malfunctions that may arise during operation.
Drum wear
The rate at which the photodrum wears out depends on:
1. Paper quality - the higher the quality of the paper, the longer the drum will last.
2. Paper density - the thicker the paper, the greater the impact on the photoconductor and the shorter its service life.
3. Paper Finish - Generally, glossy paper is not suitable for printing with a compatible image drum. The toner simply does not “stick” well to this paper and sticks to the photo drum, causing it to become dirty. The problem can be solved by constantly cleaning the drum unit.
4. Printing intensity - the more intensively the cartridge is used, the faster the photodrum wears out.
5. Using stickers - stickers create unnecessary load on the photodrum; you need to use special stickers for laser printing.
6. The use of letterhead - many companies use letterhead (printed on a color printer or in a printing house) - just like a sticker, they create additional load on the photodrum, especially since the additional load constantly falls on the same areas of the photodrum.
7. Using “turns” (sheets that are clean on one side) - the sheet passes over the photodrum with its used side, which causes the drum to wear out faster
Modes of use - you need to monitor the condition of the printer, carry out cleaning and maintenance on time, do not load more than the declared productivity
A Brief History of the Development of Laser Printers
The first step towards the creation of the first laser printers was the emergence of new technology developed by Canon. The specialists of this company, specializing in the development of copying equipment, created the LBP-CX printing mechanism. Hewlett-Packard, in collaboration with Canon, began developing controllers to ensure compatibility of the printing mechanism with PC and UNIX computer systems. The first official laser printer was released in 1977 and it was called the Xerox 9700 Electronic Printing System. Then the HP LaserJet printer was first introduced in the early 1980s. Initially competing with dot matrix printers, the laser printer quickly gained popularity throughout the world. Other copier companies soon followed Canon's lead and began research into laser printers. Toshiba, Ricoh and some other lesser known companies were also involved in this process. However, Canon's success in creating high-speed printing mechanisms and cooperation with Hewlett-Packard allowed them to achieve their goal. As a result, the LaserJet model occupied a dominant position in the laser printer market until 1987-88. The next milestone in the history of laser printer development was the use of higher resolution printing mechanisms controlled by controllers that ensure a high degree of device compatibility. Another important development was the advent of color laser printers. XEROX and Hewlett-Packard introduced a new generation of printers that supported color image representation and improved both printing performance and color accuracy. Color laser printers appeared in 1993 and cost about 12-15 thousand dollars. And in 1995, Apple released its Color Laser Printer 12/600PS for only $7,000.
Laser printer 1993 Apple LaserWriter Pro 630 Laser printer 1995 Color Laser Printer 12/600PS
Color laser printer
The principle of color laser printing technology is as follows. At the beginning of the printing process, the rendering engine takes a digital document and processes it one or more times, creating a page-by-page bitmap image of it. In the second stage, a laser or LED array creates a charge on the surface of a rotating photosensitive drum that matches the resulting image. Laser-charged small particles of toner, consisting of coloring pigments, resins and polymers, are attracted to the surface of the drum. The paper is then rolled through the drum and the toner is transferred to it. Most color laser printers use four separate passes corresponding to different colors. The paper then passes through a "furnace" which melts the resins and polymers in the toner and sets it onto the paper, creating the final image.
Laser printers can focus very precisely, resulting in incredibly fine beams that charge areas of the photosensitive drum. Thanks to this, modern laser printers, both color and black and white, support fairly high resolution. Typically, the resolution for black and white printing varies from 600 x 600 to 1,200 x 1,200, and for color printing, the resolution reaches 9,600 x 1,200.
Color and black and white laser printers work almost identically. The difference is that for color printing, four types of ink toner are used: black, cyan, magenta and yellow, according to the CMYK color model. Each color contributes to the final image placed on a sheet of paper. In some models of color laser printers, a piece of paper sequentially passes through all the color and black cartridges, where each color has its own laser, drum and toner cartridge (single-pass printing). Less expensive printers, which include most of the models discussed in this review, use an intermediate medium (transfer belt), onto which an image of all four colors is sequentially applied, and only then it is transferred to paper and enters the oven to fix the toner on the paper (multi-pass printing).
Color laser printer with a very impressive productivity of 20 thousand pages per month. Black and white printing speed 16 ppm, color 4 ppm, memory capacity 32 MB. Even toner cartridges are small and of an unusual design, resembling cylindrical cans in appearance, and are installed in front, along the paper path. In the packaging, these cartridges can be mistaken for inkjet cartridges due to their small size. The resource of the black cartridge is 1500 pages, color 1000 sheets.
Xerox Phaser 6110 The new printer from Xerox, the Phaser 6110 model, is an inexpensive solution in the entry-level segment. The low price of this model can be explained by the use of 4-pass printing technology. As a result, the printing speed in color is not very high - 4 ppm, in monochrome printing it is higher - 16 ppm. Prints on paper and films up to 164 g/m2. Small dimensions and low noise level will allow you to comfortably use the printer at home, and good performance of 24,000 pages per month makes it possible to use the device in a small office.
Oki C3450n New model from Oki - C3450n. The printer is capable of printing both business cards and on banners up to 1.2 m, Moreover, the direct paper path allows printing on fairly dense media. Color printing speed is 16 ppm, and in monochrome printing it reaches 20. The resolution is 1200x600 dpi. The monthly load is up to 35 thousand pages, and cartridges of each color are enough for 2500 pages. The design of the device is such that replacement of all consumables, even the transport belt and stove, which have a resource of 50,000 pages, is possible by the user himself, without the involvement of service specialists.
Main characteristics and features of laser printers
Print speed. Modern personal laser printers are characterized by a fairly high print speed - up to 18 ppm. But when talking about print speed, you should definitely take into account that the manufacturer indicates its maximum value for certain characteristics of page coverage and print quality. Therefore, the actual speed of printing complex graphic images with high quality prints is usually lower than that declared by the manufacturer.
Resolution and print quality. These two characteristics are closely related, because The higher the resolution, the higher the print quality. Resolution is measured in dpi, which is characterized by the number of dots per inch in horizontal and vertical ratio. Today, the maximum resolution of home printers is 1200 dpi. For everyday work, a resolution of 600 dpi is quite sufficient; a higher resolution is necessary for clearer reproduction of halftones. Increasing the resolution complicates the mechanics and electronics, and entails an increase in the cost of the printer. Also of great importance here are the characteristics of the dispersion (size) of the particles of the toner used in the printer (for example, HP uses finely dispersed UltraPrecise toner with a particle size of no more than 6 microns).
Memory is quite an important characteristic. Here you should pay attention to the availability of the processor and printer control languages. Win printers do not have built-in processors, so the job that needs to be printed is processed by the computer processor and laser control codes are transmitted to the printer via a connection cable (USB or LPT). The memory in such printers is buffered, i.e. stores a print job processed by a computer, and the size of this memory affects the speed of output of this information, and not the speed of processing data for printing. When describing a large-volume job with graphics, a situation may arise that it will be impossible to work on the computer. For another group of printers that have built-in page description languages PCL5, PCL6, PostScript, the print job is sent via cable to the printer, which uses its own memory and the processor processes the print data. In this case, the larger the printer memory, the more powerful the processor, the faster the printer will process the print job, the more processed material will fit in its memory and, therefore, the faster the printing speed.
Consumables. The availability of consumables and an authorized service center plays a very important role. Considering this condition, as well as the cost of consumables (original and compatible), the clear leader is HP, CANON; cartridges for printers from these manufacturers are sold in every specialized office equipment store, while consumables for Brother, Samsung, Lexmark, OKI you cannot always purchase quickly.. In this class of printers, cartridges are an all-in-one solution: a plastic case contains a photosensitive drum, a cleaning blade, gears and toner (the exception is OKI LED printers, which have separate photoconductors and a toner tube). After your cartridge runs out of toner, the most ideal option is to buy a new cartridge, but usually every printer owner hopes to save on the purchase of new original consumables by refilling cartridges with compatible toners. There are a large number of manufacturers of compatible toners, drums and squeegees, the most common in our market are Static Control Components (SCC), ASC, Fuji, Integral, Katun and others. It is advisable to carry out the restoration of cartridges in service centers specializing in refills, since this technology is carried out only in specially prepared places equipped with exhaust ventilation and powerful vacuum cleaners. Please remember that incorrect use of toner can damage the printer. The photosensitive drum can be used to regenerate the cartridge up to 3 times, then it must be replaced along with the cleaning blade. On average, the cost of remanufacturing is approximately 20% of the cost of a new original cartridge, and the cost of a complete regeneration with replacement of the drum and squeegee is 55% of the cost of a new cartridge. HP and Canon cartridges are restored more often than others, since they have a lower cost of restoration and complete regeneration. For Lexmark printers. Brother, Samsung, the cost of remanufacturing cartridges will be slightly higher than for HP, Canon cartridges. For OKI LED printers, restoring cartridges is categorically not recommended, since in this case the photoconductor breaks down very quickly, the service life of which is designed for approximately 20-30 thousand copies and its cost is almost half the cost of a new printer.
Advantages and disadvantages of laser printers
Despite the relatively large difference in cost between laser and inkjet printers, laser printers are a more economical type of printing device, which is especially important in cases where frequent printing of complex color images is necessary. Like any technical device, laser printers have their disadvantages and advantages.
Of the most significant benefits laser printers related to their operational characteristics, I would like to note the following:
Much faster printing speed than any inkjet printer;
Low cost of printing, which is especially noticeable when frequently printing complex color images. As a rule, the cost of a page with color printing made on an inkjet printer is several times higher;
Low cost of printing photographic images, although their quality, compared to images obtained on inkjet printers, is slightly lower.
Laser printers are more economical than inkjet printers;
Of the main shortcomings laser printers, which should definitely be taken into account when purchasing them, I would especially like to note the following:
Low quality of printing of photographic images, significantly inferior to the quality of photographs obtained on inkjet printers;
Significant energy consumption;
Laser printers, during their operation, emit fine dust from their toner, which has a harmful effect on human health;
Significant noise level when performing printing work.
The invention of the printer is without a doubt one of the greatest scientific revolutions in the history of printing since the advent of Gutenberg's printing press.
The urgent need for a printer arose in the 1950s, when electronic computers appeared. The calculations were typed by a large team of typists who scribbled on typewriters day and night.
19th century typewriter.
For companies, this was not only costly, but also fraught with errors. And then scientists thought about how to connect a computer with a typewriter. This is how the Uniprinter device came into being.
For printing, the so-called petal mechanism was used: printed characters were applied to metal movable legs, similar to petals. A petal foot with one or another sign was pressed against the paper through an ink ribbon, leaving an imprint. By changing the “petals”, it was possible to change the font or alphabet. In a minute, the machine typed up to 78 thousand characters, which is hundreds of times faster than the speed of the most agile typist.
The first commercial xerographic machine, Model A.
Further, printing technologies began to develop progressively.
The operating principle of dot matrix printers is in many ways similar to Uniprinter. With the difference that printing on paper was achieved not through an imprint, but through small needles, from a set of which the required symbol was formed.
In parallel with the needle principle, inkjet printing technologies were developed. The scientific foundation in this direction was laid by the British physicist and Nobel laureate Lord Rayleigh, who in the 19th century studied the disintegration of a liquid stream and the formation of droplets.
Various companies offered their own methods of printing with controlled ink jets. However, they all had something in common. A drop was formed at the bottom of the ink container, which, using the piezoelectric effect or an increase in temperature, was shot onto the paper. This technology was brought to fruition only towards the end of the 1970s.
The laser principle of printing, contrary to popular belief, appeared long before matrix and inkjet printers - in the late 1930s. It is based on the electrographic printing method invented by the American Chester Carlson.
Chestor Carlson with his invention.
A negative charge is applied to the aluminum cylinder (imaging drum), and then a laser beam removes this charge where printing is needed. Next, powdered paint is applied to the drum, which adheres to the “discharged” areas. And when the drum comes into contact with the paper, an imprint remains on it, which, thanks to the high temperature, reliably sticks to the surface.
This principle was used in the first photocopiers. And in 1969, Xerox specialists found a way to turn a copier into a printer. Thus, it was Xerox that stood at the origins of laser printing, and Xerox printers are still in deserved demand among both home users and office workers.
Modern printer manufactured by Xerox.
However, not all of them know that not so long ago a new, solid-ink printing technology appeared, which in some respects is superior to laser technology. Currently, Xerox is the only company producing solid ink printers.
However, solid ink technology is a separate topic.
If you look into the past, laser printing technology appeared earlier than dot matrix printers. In 1938, Chester Carlson invented a printing method called electrography. This principle is used in all modern laser printers.
It consists of the following: a negative static charge is applied to an aluminum tube (photodrum), coated with a photosensitive layer. After this, the laser beam passes through the photodrum, and in the place where something needs to be printed, it removes part of the charge. After that, toner is applied to the photodrum (this is dry ink consisting of a mixture of resins, polymers, metal shavings, coal dust and other chemicals), which also has a negative charge, and therefore sticks to the drum in those places where the laser passed and removed the charge. Then everything is simple: the drum rolls over the paper (which has a positive charge) and leaves all the toner on it, after which the paper goes into the oven, where under the influence of high temperature the toner is firmly baked to the paper.
To print a color image, all colors are applied to the drum one by one, or printing occurs in 4 passes (for printing black, cyan, magenta and yellow). A similar printing method is used in photocopiers and some fax machines. A similar system is used in LED printers, but instead of a laser, they use a fixed line with LEDs - LED printing technology (Light Emitting Diode). And the laser printer itself appeared like this: a certain Gary Starkweather, an employee of Xerox, came up with the idea of using copier technology to create a printer.
Thus began the development of the first laser printer in early 1969. And it was published in November 1971. The device was called EARS, but it didn’t go beyond the laboratory. If you believe the documents, the first official laser printer was called the Xerox 9700 Electronic Printing System, and was released in 1977. At the same time, IBM claims that in 1976 their IBM 3800 laser printer was already printing in full swing at the F.W. Woolworth North American Data Center. Later, in May 1981, Xerox introduced the Star 8010 computer, which included the latest developments such as a WYSIWYG text editor, a graphics editor, a text and graphics editor, and, of course, a laser printer. All this fun cost only $17,000. It was something like a home printing press.
Three years later, Hewlett-Packard released the LaserJet printer, with a resolution of 300 dpi and a price of $3,500. The same year, Apple supplied prototypes of its LaserWriter printer to companies such as Lotus Development, Microsoft and Aldus. And in 1985 and 1986, Apple LaserWriter and LaserWriter Plus appeared, respectively. And in 1990, Hewlett-Packard LaserJet IIP printers began to cost less than $1,000 for the first time. And the LaserJet III series began to use improved resolution technology (RET - Resolution Enhancement Technology). And two years later, the same HP began selling a truly popular laser printer, the LaserJet 4, which, in addition to its relatively low price, had a resolution of 600 dpi. But in the same year, Lexmark pushed HP into the laser printer market by releasing Optra series devices with a resolution of 1200 dpi.
Color laser printers appeared only in 1993. QMS introduced the ColorScript Laser 1000 for just $12,499. Two years later, Apple released its Color Laser Printer 12/600PS for just $7,000.
Laser printers have now become noticeably cheaper. They are becoming increasingly popular, but they are not yet cheap enough to compete with inkjet printers.
Last time we looked at the history of printing from ancient times to the invention of the first printer. It was full of secrets and very ambiguous, which you, dear habro-people, kindly noted in your comments. Today we are talking about the history of personal printing, the development of which began in the mid-twentieth century.
One of the first mass-produced dot matrix printers was the LA30 from DEC (Digital Equipment Corporation). This device was capable of printing only capital letters measuring 5 by 7 dots at a speed of 30 characters per second on special sized paper. The print head of this printer was controlled by a stepper motor, and the paper was pulled through a drive with a ratcheting mechanism - not very reliable and noisy. Interestingly, the LA30 had both a serial and parallel interface.
However, it was the DEC LA36 printer that actually became a symbol of printing technology, winning public recognition in its time. The developers have corrected major errors and shortcomings, and also increased the line length to 132 characters of various registers. As a result, standard perforated paper was suitable for printing. The carriage was driven by a more powerful servo drive with an electric motor, an optical position sensor and a tachometer. All this made the printer more convenient and reliable.
Another interesting technical feature of the LA36 is that without accepting more than 30 characters per second from the computer, it printed twice as fast. The fact is that when the carriage was returned, the next packet of characters ended up in the buffer. Therefore, when printing a new line, the printer caught up at a speed of 60 characters per second. LA36 set the “fashion” for multi-tone typing sounds - in fast and normal mode. After all, its head moved in one direction at one speed, and in the other at twice the speed, creating a kind of office noise background.
But the most popular and best-selling model until the 90s was the Epson MX-80, which combines relative affordability and good performance parameters for that time. Matrix printing technology dominated the market for a long time, but in recent years, thanks to the development of such areas as inkjet and laser printing, as well as their varieties, it has given them the main niche and gone into the shadow of specialized solutions.
Inkjet printing
If we start from the very beginning, we can consider the birth of inkjet printing to be 1833, when Felix Savart discovered and stated the uniformity of the formation of liquid droplets released through a narrow hole. A mathematical description of this phenomenon was carried out in 1878 by Lord Reilly (who later received the Nobel Prize). But it was only in 1951 that Siemens patented a working device capable of dividing a jet into droplets of the same type. This invention led to the creation of the mingograph, one of the first commercial recorders used to record voltage values.
When talking about inkjet printing, we must not forget about such an approach as drop-on-demand. Not many people remember this today, but the first inkjet printers had a serious problem with removing droplets that should not have gotten onto the paper. The essence of the drop-on-demand method is that the device releases drops of ink only when necessary.
The first developments in this area were applied in the Siemens PT-80 sequential character printing device in 1977, as well as in the Silonics printer, which appeared a year later. These printers used a prototype of piezoelectric printing, where ink droplets were released by a pressure wave created by the mechanical movement of a piezoceramic element.
In 1979, Canon invented drop-on-demand printing, in which droplets were released onto the surface of a small heater located next to the nozzle and controlled by condensation of mist-like accumulations of dye. Canon called this technology “bubble printing”.
In 1980, Hewlett-Packard independently developed a similar technology called thermal inkjet printing, and already in 1984 the ThinkJet solution appeared on the market - the first commercially successful and relatively inexpensive inkjet printer that provides good print quality and resolution.
Inkjet technologies are developing today, providing multi-color printing, printing on large formats, they allow the use of both soluble and pigment dyes (when minimal particles of ink penetrate through the nozzle and settle on the paper). Modern inkjet printers can be said to be in a state of progress and are actively fighting for their place in the sun. Improvements in print speed and ink resistance to time, moisture and friction, as well as lower cost per print, have made them a serious competitor to laser and LED printers.
Back in 1971, the first prototype of a laser printer appeared, but it was only in 1977 that XEROX released the Xerox 9700 Electronic Printing System. In 1981, Xerox continued its development and released the STAR 8010 computer. Along with it, graphics and text editors were sold, as well as a program for combining texts and graphics and, of course, a laser printer. The cost of such equipment at that time was $17,000.
The next important stage in the history of laser printers occurred in 1984. Then Hewlett-Packard began producing a series of affordable LaserJet printers, which provided an excellent resolution of 300 dpi at that time. In 1992, HP released its LaserJet 4 printer, costing slightly less than $1000 and with a resolution of 600 dpi. We can say that this moment became a turning point and laser printers began to gain popularity and conquer the office printing market.
LED Printers
LED printers are rightfully considered more technologically advanced than laser ones. Instead of a laser, they use a long line of LEDs that flash selectively to create an electronic pattern on the drum. Thus, this technology is more economical and allows for higher printing speeds, all other things being equal (design of the printing mechanism, interface speed, CPU used, etc.). The first LED printer was released by OKI only in 1987, and 10 years later, in 1998, the company also developed the first color LED printer.
LED printers appeared in our country in 1996 with the opening of the OKI regional office. In 1999, Panasonic and Kyocera began supplying LED printers to Russia.
The history of LED printers in Russia is closely connected with the budget and home model OkiPage 4W, which was positioned in our country as a basic model for the office. OkiPage 4W turns out to be significantly cheaper than its laser counterparts, and its sales in the business segment are off to a very strong start. However, those designed for home printing volumes (2500 pages per month) quickly fail, both due to excess load and poor-quality refill materials. It is believed that it is precisely because of this situation that LED printing is still not so popular in Russia.
However, at present, LED printers continue to actively develop, offering a worthy alternative to classic laser models. The range of manufacturers includes both standard color and black-and-white, as well as large-format LED printers.
Sublimation printing
At the request of workers, we will say a few words about technologies such as sublimation printing and Micro Dry. They appeared relatively later than laser and inkjet printing, and perhaps that is why they have not yet taken a significant place in the market.
The pioneer of sublimation technology is considered to be the Frenchman Noel de Plasset. In 1957, Noel de Plasset discovered that some dyes can sublimate, that is, pass from a solid to a gaseous state, bypassing the liquid state. However, in the 60s, his discovery did not affect the press, although 20 years later, with the spread of personal computers and the development of technology, his ideas became relevant again. In 1985, they began to use thermo-sublimation printing in practice, actively using photo printers from Kodak for direct printing from cameras, as well as from Mitsubishi Electric. However, the scope of application of this technology is very limited, since printing requires special thermal paper, and the speed of pattern transfer is quite low, because each color dye is applied to the paper one by one.
Micro Dry printing technology was developed in 1996 and is primarily used in Citizen printers. Its essence is to apply a solid dye directly to the carrier. This ensures the ability to print with the same quality on any paper, including metallic dyes. Printers can print with a resolution of up to 600x600 in color, but the cost of a print is still quite high.
Conclusion
Here we briefly talked about the history of the development of printing, but we should not forget that today new technologies continue to be developed. For example, we recently talked about
