Where is the laser in the laser printer. Laser printing - basic principles of work

Laser printing devices are in great demand for office needs. This technique is used for home. Excellent consumer qualities due to the principle of work laser printer. About this as well as about constructive features The apparatus, its merits and disadvantages will be discussed in this material.

Essence of laser printing technology

The printing process in the laser printer is based on printing technology on paper with dry ink under the influence of static electricity invented in 1938. In the late 70s, to automate work in copying machines The laser beam began to be used. After almost 20 years of improvement, technology has allowed to produce laser desktop location devices.

In modern laser printers, as well as MFPs with a scanner and a copier, an image is formed by photovoltaic xerography and is fixed under the influence of heat with a special toner, which replacement cartridges are refilled.

Constructive elements of the laser printer

Regardless of the model, any laser printing device has a modular design of the following parts:

• laser scan module ( printed circuit board);
• image forming unit (cartridge);
• paper supply unit;
• thermoshel.

The circuit board is a lid-protected module consisting of the following elements: a semiconductor laser with a lens focusing beam rotating using a mirror motor, a group of guide laser beam lens, as well as mirrors.

Important! The laser beam generated by the printed circuit board is sent to the forming image module - cartridge.

Feature design cartridge

The design of the laser printer is a separate remedy case with inside elements, the purpose of which "for dummies" is not too clear. Among them:

• photosensitive drum;
• charger;
• raquel for cleaning photoshot from residual particles;
• tank with toner;
• magnetic shaft with a core;
• powder dosage driver, the so-called "doctor";
• seal (removed when installed in the printer).

Unlike matrix and inkjet models Printers that have symbols transmitted by the processor to the printed head are reproduced on paper by painting tape or paint drops, the printing process in the laser machine is multi-step. So, first the preliminary charge of the photobaban occurs, then the coverage of the hidden image with a laser, then transferring the print on paper with its subsequent heat treatment.

Basic consumables

The main consumables of laser printing equipment is the cartridge. After an important node has developed its resource, the user has three maintenance options.

1. Buy new The original instance for replacement, which is quite expensive.
2. Purchase compatible Print knot from third-party manufacturer. This is an acceptable economy option.
3. Take advantage of the services of a service company specializing in the repair and maintenance of office equipment, in the list of services of which is recovery / refueling cartridges. This is a super-economy option. But after 3-4, the loading of the freight is beaten, and you will have to use 1 or 2 option.

The process of formation of imprint on paper

When you turn on the device is translated into the ready-to-print state. The internal elements of the printer come into motion, heats up the thermal suite, which is accompanied by a sound characteristic of printing, but at this moment the laser beam does not turn on. Next, the device subsides, and the indicator on its housing lights up, signaling readiness to work. When a document print command is received on the device, a multi-step process of forming a printed sheet is initiated.

On a note! Laser printing equipment To control the image output process on paper is supplied with a built-in processor. Also, many high-speed office models are equipped with built-in memory.

Charge of photobraban

When the device is ready for work receives a print command, all the mechanisms responsible for this process are given in motion: printed circuit board, cartridge, paper feed. Also, the cartridge preparation is also occurring, during which the photo charge is carried out - on the photosensitive elements of the drum is transmitted electric charge When contacting the rotating PCR roller. The latter receives a recharging when the printer is turned on.

Depending on the manufacturer of printing equipment and the toner used to be transmitted may be negative or positive. In digital models of HP, Xerox, Canon, Ricoh, Samsung, the combination of toner and photo cylinder charges - both negative. Accordingly, Epson, Kyocera, Brother - both positive.

Exposure to laser beam

In the second stage of the image formation, a laser beam is turned on by exponentially. The focused laser beam is reflected from the mirror and falls on the guide system of lenses, and then goes to the required place on the rotating photo cylinder.

Important! The symbolic string on the photosensitive layer is formed from the marked individual points, which are created successively with a redirected laser beam. Under its exposure to the photo-point losing charge. Thus, from neutrally charged points and a hidden image of a page is formed.

Manifestation of an image

The next step is to apply a toner consisting of a dye with special charged additives. As a result of this procedure, an image is manifested on the photosensitive layer. The process occurs as follows.

1. The magnetic shaft, the part of which is in the filling compartment, attracts the powder particles, and those through the "doctor" dosage portions are sent to the photosensitive drum.
2. From charged areas (not treated with a laser beam), particles are repelled and stick to the points lost charge. Thus, the hidden image becomes visible.

Printing paper and clipping image

When contacting the phototraban with paper, which is served by the transfer roller with the opposite electrical charge, the dye attracts to the sheet, Forming prints. Paint particles are held due to static electricity. The toner graums remaining in the drum wonder the rocket in the hopper for waste.

The image is recorded using heating. The sheet with the toner is stretched between the presser and heating elements. Under the influence of the stove, coloring particles are swapped into the paper structure. After the output, the dye quickly freezes, and the printed image becomes stable.

Upon completion of the image formation process on a paper sheet, the photo jack of the drum is restored by charging rollerand then on the cycle scheme continues work on the seal of the following pages

Color laser printing technologies

The basic principle of formation and receipt of print on paper in the color version is identical to monochrome laser printing. To reproduce a multicolor picture, 4 images of different shades used in color printing are created and superimposed on each other: black, blue, purple and yellow.

On a note! The full color picture can be created one of two ways: according to the multi-frequency or single-pass technology.

Multiple Principle Printing

When forming color imprint on a multi-proper principle, the printer is equipped with a revolver with 4 toner tanks. The technology also involves the use of auxiliary media (belt), to which the image of one color is transferred to each pass. After the formation of all 4 multi-colored sketches, a full-color image from the transfer belt is imprinted on paper, and then the resulting impression is fixed under the influence of heat. Multipurifuge technology pretty slowAnd it is used in budget models of laser color printing devices.

Single-pass image formation

In order for the full color picture to be formed in one pass, the laser equipment is equipped simultaneously working in the tandem version by four non-ferrous mechanisms. Each of them has its own freeware and toner tank with a dispenser. Paper using a roller conveyor takes place under each photosensitive element where toner is transferred to it. Formed in one pass, the color picture is fixed when the heating element is broken. The single-pass print cycle is equipped with high Speed expensive models.

Advantages and Disadvantages of Laser Print

Laser office equipment is very popular, high-tech and productive. Many users give her preference for such advantages:

• high performance;
• big resource opportunities;
• low printed cost;
• unpretentiousness;
• rapid drying of print;
• persistence of a sealed image to external influences (moisture, heat);
• low noise when working;
• long-term storage of toner, excluding paint drying;
• high print speed, etc.

These are the main advantages of representatives of all price segments, thanks to which laser technique leads in demand.

but specifications Laser output devices are not suitable for printing complex 3D graphics, photos, files in GIF format. Another disadvantage can be called the cost of devices - the most affordable apparatuses are 2-3 times more expensive.

Briefly summarizing the above information, it should be noted that laser managers of office equipment are in demand when it is necessary to print a lot and quickly. However, this does not concern photographic writing, since they are presented with increased requirements for the color rendering, which will not be able to provide laser devices. More information about this printing technology can be viewed on the thematic video.

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Modern printers for the most part according to the technology of work are divided into laser and inkjet. Moreover, thanks to progress, the second managers are gradually leaving the market, remaining specialized. In offices, houses and even some print centers, you can most often find the laser printers.

In domestic use, the main difference of inkjet printers from laser is primarily in the high economy of the latter. Ink consumption is almost minimal - one cartridge is enough for several thousand sheets with a fairly large painting density. In addition, laser printers work very quickly and do not require special service care.

Contrary to popular belief, the laser printers do not "burn out" characters on paper. Special toner is used to apply an image. It is he who sticks to a paper sheet, leaving characters or pictures. By the way, because of this feature of the technology, colored laser printers are practically not found, in contrast to monochrome (black and white).

Basic Laser Printer Functional Nodes

Design of any laser printer regardless of specific modelThe manufacturer and capabilities include several main functional nodes:

• drum. It is a toner to be applied to it by means of electrostatic attraction and repulsion according to the law of the coulon;
• raquel. It is designed to clean the drum from toner residues before applying new;
• coronator. This device is designed for electrostatic charging of the drum;
• laser and mirror system. Being a source of coherent electromagnetic radiation, it dots discharge the drum;
• magnetic shaft. The toner is fixed on it for subsequent transfer to the surface of the drum;
• stove. It is designed to baked toner left on paper. Therefore, the sheets released from the laser printer have a sufficiently high temperature;
• management model (controller) - Microprocessor system that controls all this equipment.

Both colored, and monochrome laser printers are based on these functional nodes. Only the system and capabilities change. For example, four drums are installed in colored laser printers - for each of the fundamental colors (red, yellow, blue and black) - and the so-called transfer tape, which is designed to transmit an image formed by the corresponding toners, on paper.

Laser printer action principle

The principle of the operation of the laser printer in the abbreviated description is quite simple. The full difference from one model to the other, however, some fundamental elements are present in each case:

1. The drum is cleaned. The rocket knife removes the sticking knob, but not used in the previous toner seal cycle;
2. The coronator charging the surface of the drum. It arises or positive ions, or the number of negative electrons increases. It is intended for the emergence of Coulomb forces.
3. A laser controlled by a swivel mirror partially discharges the surface of the drum. Toner itself is negatively or positively charged. Therefore, it is repelled from the charged areas of the drum area and attracts to the discharged. Again, this is due to the action of Coulomb forces.
4. From the surface of the magnetic shaft on the drum, powder toner is transferred.
5. From the surface of the drum, the toner joined it is transferred to a paper sheet.
6. The paper is sent to the "furnace", consisting most often from the heating element in the form of a halogen lamp and a presser roller. The toner is fixed due to melting under the action of high temperature and due to the pressure from the side of the shaft fixed on the spring.

If 4 separate drums and as many magnetic shafts are installed in color laser printers, but the toner is not applied to the paper itself directly, but on the transfer tape. All four shades are first applied to it. Then the transfer tape is rolled through paper, and the multicolored image turns out to be on the sheet. Then the toner is baked and fixed.

Fundamental non-technological differences between laser and jet printers

Laser printers are recently more popular than inkjet. If we abstract from technological differences, then they possess the following advantages:

• efficiency. The laser printer cartridge is enough for several thousand sheets of paper with high filling.
• the possibility of refueling. Laser printer cartridges can be charged with toner if necessary without the risk of violations of their functionality. You can even conduct this operation yourself, but it should be careful because the coloring pigment is negatively or positively charged and under the action of Coulomb forces quickly sticks to the skin, clothing and other surfaces. Inkjet printer cartridges in most cases cannot be refueling, as this leads to a disruption of their tightness. For some models of this type, the ink continuous supply systems can be used, however, this is considered as unauthorized modification and leads to a warranty agreement.
• high speed. Most models of laser printers can print up to 10 pages with text per minute. Some work even faster.
• no need for weekly press. Toner used in laser printers does not dry and does not stick. Therefore, periodically "drive the seal" to prevent the head clogging, do not need. Actually, there is no head in laser printers.
• durability of prints. Images and text on paper, obtained using such office equipment, do not fade and do not disappear over time under the action of high humidity.
• high resolution image. Colored laser printers provide permission when printing up to 9600 x 1200 dpi.

However, they also have some drawbacks compared to inkjet printers:

• horregious. On average, the laser printer in the configuration "from the plant" is, that is, with incomplete cartridges - stands several times more than a similar inkjet. For monochrome, this is a 2-3-fold increase in price, for color - 10 times and higher.
• dorganiza cartridges and toner. Consumables for laser printers are 2-3 times more than for inkjet. However, it is worth considering that their limit of use is also 2-3 times higher.
• bulkiness. Laser printers are usually several times more than inkjet. It is also explained by the complexity of the design. As a result, they require a separate place to install.
• the need to warm up before work and the risk of overheating after prolonged printing. Despite the fact that the design of the "stove" includes a special thermoelement, which does not allow the temperature to achieve a critical mark, in some cases it may fail or work inadequately. After that, there is an overheating of the device with the risk of system problems.
• small ecology. When working, such devices are separated into the air some harmful compounds, dust, and emissive infrared and ultraviolet radiation.
• high resource intensity. Due to the presence of "voracious" in relation to the current elements, laser printers consume more electricity. Moreover, peak power can be so high that such an office equipment will not work from domestic or office UPSs.
• impossibility of stable repetition of full-color images Due to the uncontrolled effect of electromagnetic fields.

Thus, laser printers have both advantages and disadvantages compared to inkjet. However, in some use scenarios, they show themselves as much more optimal or useful than analogues.

Before answering the question of how the laser printer works, it should be noted that the first image obtained by C. Carlson with the use of static electricity and dry ink belongs to the 1938th year. But the first prototype of a modern laser device was created in the mid-50s of the last century. It should be added that the principle of operation of the laser printer is based on the process of the so-called. Laser scan. After the document is scanned, there is an overlay and transfer of the coloring substance, as well as the fixing of the finished image. A similar principle of laser printing allows you to print text and graphics on ordinary paper with a sufficiently high speed. Learn more about how the laser printer prints is below.

If we talk about what is a device of a laser printer, then it must be said that any model of this device consists of a phototraban, a laser block, a transfer node and a fixing unit. In addition, in the cartridges, depending on the model uses a magnetic shaft or a manifest roller. Paper is fed to print using a special node responsible for this action.

To answer the question in more detail how the laser type printer is arranged, it is also necessary to tell about the paint (toner) used in this office equipment. So, the toner is a substance consisting of very small particles of polymer coated with dye, with the inclusion of magnetite. In addition, it includes the so-called. Charge regulator. Depending on the manufacturer, all similar powders are characterized by indicators such as density, dispersion, grain size, magnetism, etc. For this reason, filling the laser printer of any random powder paint is not worth it, because This will worsen print quality.

Office equipment of this type, as a monochrome printer / MFP, has been widely used for personal use, i.e. at home. Its main advantage is available in the available cost, which is due to the fact that such devices do not need a large number of software resources or memory. They only need a controller that will allow the most basic function, which is to print all kinds of documents. In general, it can be used to print ordinary text or some black and white diagrams and schemes where the presence of color does not play much. Other advantages of monochrome devices of laser type are in low cost of consumables, maintain large loads and printing capabilities large number Pages. But a similar device of the printer does not allow it to print color photos and complex schemes. In addition, such a device does not have high print quality.

As for color laser printers, their advantages are in good print speed and the possibility of printing color schemes, images and photos. But note that such a printing device is quite expensive, which, in turn, significantly narrows its accessibility. Other minuses are low profitability due to the high cost of consumables, high power consumption and not enough high quality Color images. Those. Such a device is not suitable for printing professional photos.

But all types of laser printers, as a rule, have the same principle of operation. Differences are only in their value and functional opportunities and parameters, for example, such as the resolution of the laser printer. As for the direct printing process, it can be divided into five key stages described below.

First Stage: Photobraban Charge Education (Fotoval)

To answer the question of how the laser printer is arranged and how it works, it should be said that one of its main devices is a print drum covered with a special semiconductor that has high photosensitivity. It is on it in the first stage and an image is formed intended for further printing. To do this, this item is supplied with a charge with a plus or minus sign. This is done, as a rule, using a bitter (coronator) or charging shaft (charge roller). The first is a block consisting of a wire, around which there is a metal frame, the second is a metal shaft covered with foam or conductive rubber.

The first method of imparting a certain charge with the use of the coronator is that under the action of voltage between the frame and the wire (tungsten filament with platinum / gold / carbon coating), a discharge is formed. After that, an electric field is formed, which, in turn, transfers the phototrabane of the static type charge.

The use of the coronator has a whole number of minuses, which are concluded that the cluster on its threads of paint / dust particles or its bend can lead to a sharp reduction in print quality, strengthening the field of electricity in a certain place and even damage to the surface of the photobaban.

As for the second method, the charge roller in contact with the drum supplies its surface that is characterized by high photosensitivity to a certain charge. The voltage on the roller is an order of magnitude lower below that, in turn, solves the problem with the advent of ozone. But to carry out the charge of the charge must necessarily contact. Consequently, the details of the printer are in this case faster.

Second Stage: Exposure

The purpose of this stage is to form on the surface of the phototrabane with increased photosensitivity of an invisible image from points, and without using a static charge. To do this, a thin laser beam shines on a four-or-hex mirror mirror, after which it is reflected and falls on the so-called. distributing lens. He sends it to a specific place on the surface of the drum. Next, a system consisting of several lenses and mirrors moves a laser beam along the photo, as a result of which a string is formed. Because Printing is carried out using points, the laser is constantly turned on and off. The charge is also removed in a pointwise. After the string comes to an end, the photoman begins to rotate with a step-by-step motor and the exposure procedure continues.

Third Stage: Mante

Another shaft existing in the laser printer cartridge is a metal tube inside which there is a magnetic core. The magnet, inside the compartment attracts the toner tree to the surface and, rotating, takes out it out. A special dosing blade allows you to regulate the thickness of the coloring substance layer and prevent it, thus, its uniform distribution.

After that, the paint falls between the drum and the magnetic shaft. In the areas that have passed the exposure toner begins to attract to the surface of the photo, and on charged - repel. The coloring substance remaining on the magnetic roller, as a rule, goes on and passes again through the bunker. As for Toner, moving to the surface of the drum, he makes an image on it visible, after which follows, i.e. To paper.

Fourth Stage: Transfer

A sheet of paper that was served in the device passes under the photo. Under the paper at the same time there is a so-called. An image transfer shaft that contributes to the toner existing on the drum surface, hit the surface of the paper. On the core of the roller, made of metal, is supplied with a plus sign, which is transferred through the rubber coating to paper. The microscopic toner particles moved to the surface of the sheet hold on it solely by static attraction. All powder particles that remain on the photardbanks, pork paper and dust are sent using a rochel or cheeper into a bunker, specially intended for waste. As soon as the photo completes the entire cycle, the charge / huror roller again contributes to the recovery on its surface of the charge and all the work is repeated again.

Fifth Stage: Fastening

The toner used in laser printers must necessarily have the ability to melt at high temperature indicators. Only thanks to this property, it can finally gain on the surface of the paper.

For this, the sheet is stretched between two shafts, one of which presses it, and the other is heated. Due to this, microscopic particles of the coloring agent seems to be fused into the page structure. After leaving the stove, the powder quickly froze, with the result that the printed picture or text becomes rather stable.

It should also add that the upper roller, which warms the paper sheet in the form of a thermofilm or the Teflon shaft. At the same time, the second option is considered longer and reliable. However, it is expensive and used most often in the devices that must withstand large loads. The first option is less reliable, and use it usually for printers intended for small offices and use at home.

Laser printersprovide higher quality than inkjet printers. The most famous firms - the developers of laser printers are Hewlett-Packard, Lexmark.

The principle of operation of the laser printer is based on the method of dry electrostatic transfer of the image, invented by Ch.F. Karlson in 1939 and is also implemented in the copiers. The functional diagram of the laser printer is shown in Fig. 5.6. The main element of the design is rotating drumserving an intermediate medium with which the image is transferred to paper.

Fig. 5.6. Laser printer functional diagram

Drum It is a cylinder covered with a thin film of a lightweight semiconductor. Usually, zinc oxide or selenium is used as such a semiconductor. A static charge is uniformly distributed over the drum surface. It is provided by a thin wire or a grid called a coronating wire, or a huror. This wire serves high voltage, causing the occurrence of a luminous ionized area around it, called the crown.

Laser, A microcontroller controlled generates a thin light beam, reflected from the rotating mirror. The scan of the image occurs in the same way as in the television kinescope: the movement of the ray on line and frame. With the help of a rotating mirror, the beam slides along the cylinder, and its brightness varies with a jump: from full light to complete darkness, and the cylinder is also charged (stop). This beam, reaching a drum, changes it electric charge At the point of touch. The size of the charged area depends on the focus of the laser beam. Focusing the beam with the lens. The sign of good focus is considered the presence of clear edges and angles in the image. For some types of printers in the process of recharging, the potential of the drum surface decreases from 900 to 200 V. Thus, on the drum, an intermediate carrier, a hidden copy of the image in the form of electrostatic relief occurs.

At the next stage, the photophonation drum is applied toner - Paint, which is the smallest particles. Under the action of a static charge, the particles are easily attracted to the surface of the drum at the exposure exposure points, and form the image is already in the form of a color relief.

Paper It is drawn from the feed tray and with the help of the rollers system moves to the drum. Before the drum, the short-rone reports the paper static charge. The paper then comes into contact with the drum and attracts a toner particle charged by its charge, applied earlier on the drum.

To fix toner, the paper is skipped between two rollers with a temperature of about 180 "C. After the end of the printing process, the drum is completely discharged, cleared from adhesive unnecessary particles to implement a new printing process. Laser printer is pictured, i.e. forms a full page to print.

The process of operation of the laser printer From the time of receipt of the command from the computer before the printed sheet is released, you can divide into several interconnected steps, during which such functional components of the printer are involved as cPU; Scanning processor; Mirror engine control board; ray brightness amplifier; Temperature control unit; Sheet feed control unit; Paper handling control board; interface board; Power Supply; Button board and control panel indication; Additional RAM expansion fees. In fact, the functioning of the laser printer is similar to the computer: the same central processor on which the main functions of the relationship and management are focused; RAM, where data and fonts, interface cards and control panel board communicating the printer with other devices, a print node that issues information on a sheet of paper.

Colored laser printers begin to actively conquer the print market. If a few years ago, the color laser print was for most organizations and especially for individual citizens something inaccessible, now buy a color laser printer can afford to wide circle users. A fast-growing color of colored laser printers leads to what is growing and interest in them from technical support services.

Principles of color seal

In printers, as in the printing area to create color images applies subtractive color model, not additive, as in monitors and scanners, in which any color and shade is obtained by mixing three main colors - R. (red), G.(green), B.(blue). The subtractive model of flowers is called so because to form any shade it is necessary to subtract out of white "extra" components. In print devices to obtain any shade as basic colors use: Cyan. (blue, turquoise), Magenta.(purple), Yellow(yellow). This color model was named CMY According to the first letters of the main colors.

At the subtractive model, when mixing two or more colors, additional colors are obtained by absorbing some light waves and reflections of others. Blue paint, for example, absorbs red and reflects green and blue; Purple paint absorbs green and reflects red and blue; And the yellow paint absorbs blue and reflects red and green. When mixing the main components of the subtractive model, you can get different colors that are described below:

Blue + Yellow \u003d Green

Purple + yellow \u003d red

Purple + blue \u003d blue

Purple + Blue + Yellow \u003d Black

It is worth noting that all three components must be mixed to obtain black color, i.e. Blue, purple and yellow, however, get high-quality black color in this way, almost impossible. The resulting color will not be black, but rather dirty gray. To eliminate such a shortage of three primary colors, another one is added black. Such an extended color model is called CMYK.(C.yan- M.agenta- Y.ellow-blac. K. - Blue-purple-yellow-black). The introduction of black color can significantly improve the quality of color rendering.

HP Color LaserJet 8500 printer

After we discussed the general principles of building and working color laser printers, it is worth reading more detail with their device, mechanisms, modules and blocks. It is best to do on the example of some printer. As such an example, let's take a printer of the company Hewlett-Packard Color LaserJet 8500.

Its main characteristics are:
- Resolution: 600 DPI;
- Print speed in the "color" mode: 6 ppm;
- Print speed in "black and white" mode: 24 ppm.

The main nodes of the printer and their mutual location is shown in Fig.5.

The formation of the image begins with the fact that the residual potentials are removed from the surface of the photobraban (neutralized). This is done in order for the subsequent charge of the photobaban to be more uniform, i.e. Before charge, it is completely discharged. The removal of residual potentials is carried out by testing the entire surface of the drum by a special lamp of the preliminary (conditioning) exposure, which is a line of LEDs (Fig. 7).

Next, high-voltage (up to -600v) is created on the surface of the photobaban. The drum is charging in the form of a roller of conductive rubber (Fig.8). A variable voltage of sinusoidal shape with a negative constant component is supplied to the bitter. The variable component (AC) provides a uniform distribution of charges on the surface, and the constant component (DC) charges the drum. The level of the constant component can be adjusted when changing the print density (toner density), which is done using the printer driver or adjustments through the control panel. An increase in the negative potential leads to a decrease in density, i.e. To a brighter image, a decrease in the potential - on the contrary, to a more dense (dark) image. Photored (its internal metal base) must necessarily be "grounded".

After all this, an image in the form of charged and uncharged sections is created on the surface of the photardeaban laser beam. Light beam of the laser, falling on the surface of the drum, discharges this site. The laser is given to those areas of the drum on which the toner should be. Those areas that should be white, the laser is not laser, and they remain a high negative potential. The laser beam moves along the surface of the drum using a rotating hexagon mirror located in the laser assembly. The image on the drum is called a hidden electronic picture, because It is presented in the form of invisible electrostatic potentials.

The hidden electronic image becomes visible after passing through the manifestation node. The developing module of the black toner is stationary and is in constant contact with the photo-tumble (Fig. 9).

The color developing module is a carousel mechanism with an alternate supply of "color" cartridges to the surface of the drum (Fig. 10). Black toner powder is a magnetic one-component, and colored powders are one-component, but non-magnetic. Any toner powder is charged to a negative potential due to friction on the surface of the developing shaft and the dosage rocket. Due to the difference in the potentials and the Coulomb interaction of charges, negatively charged toner particles are attracted to those parts of the photobraban, which are discharged with a laser and repel from areas with high negative potential, i.e. from those who have not been laser laser. At each moment of time, the manifest is carried out with a toner of only one color. At the time of the developing on the developing shaft, the bias voltage is supplied, which causes the transfer of toner from the developing shaft to the freak brand. This voltage is a variable rectangular voltage with a negative constant component. The level of constant component can be adjusted when the toner density changes. After the end of the manifest procedure, the image on the phototrabane becomes visible, and it must be transferred to the transfer drum.

Therefore, the next step in creating an image is the transfer of the manifested image to the transfer drum. This stage is called the primary transfer step. Toner transfer from one drum to another occurs due to the electrostatic difference of potentials, i.e. Negatively charged toner particles must be attached by the positive potential on the surface of the transfer drum. To do this, a positive voltage of DC offset from a special power source is supplied to the surface of the transfer drift dripping, as a result of which the entire surface of this drum has a positive potential. With full color printing, the displacement voltage on the transfer drum should constantly increase, because After each pass, the amount of negatively charged toner on the drum increases. And so that the toner can be transferred and fall over the already existing toner, the transfer voltage increases with each new color. This image formation phase is shown in Fig.11.

In the process of carrying toner on the transfer drum, individual toner particles can remain on the surface of the phototraban, and they must be removed so as not to distort the subsequent image. To remove toner residues in the printer there is a photobaban cleaning unit (see Figure 17). The composition of this module has a special shaft - a hand to remove the charge with a toner and the photobraban - it loosens the strength of the toner attraction to the phototrabane. There is also a traditional cleansing rocket, which scraps a toner into a special bunker, where it is stored until the clearative module is replaced or will not be cleaned.

Next, the photo is again charged (after the pre-discharge), and the process is repeated until the image of the corresponding color is completely formed on the transfer drig. Therefore, the size of the transfer drum must fully comply with the print format, i.e. In this model of the printer, the circumferential length of this drum corresponds to the length of the leaf of the format A3 (420 mm). After applying the toner of one color, the image formation process is completely repeated with the only difference that the developing block of another color is used. To use another developing node, the carousel mechanism turns to the specified angle and brings the "new" manual shaft to the surface of the photobaban. Thus, when forming a full-color image consisting of four color components, the transfer drum turns four times, and on each turn to an already existing toner is added toner of another color. At the same time, the first is applied yellow powder, then purple, then the blue powder is applied the blue and the latter. As a result, a full-color visible image, consisting of particles of four multi-colored toner powders, is created on the transfer drig.

After the toner powder turns out to be on the surface of the transfer drum, it passes through the additional charge unit. This unit (Fig. 12) is a wire short, which is supplied to an alternating voltage of the sinusoidal shape (AC) with a negative constant component (DC). This voltage toner powder is additionally charged, i.e. Its negative potential becomes higher, which will contribute to a more efficient transfer of toner on paper. In addition, the additional voltage reduces the value of the positive potential of the transfer drum, which helps the correct location of the toner on the transfer drum and prevents the offset of toner. As a result of this - accurate reproduction of color shades. The voltage of the additional charge is supplied to the transfer drum during the application of yellow toner, i.e. At the very beginning of the image formation process. When applying a yellow toner powder, the voltage of the additional charge is installed on minimum valueAnd after applying each new color, this voltage increases. The maximum voltage of the additional charge is supplied during the application of black toner.

Next, a full-color visible image from a transfer drum should be transferred to paper. This transfer process received the name of the secondary transfer. Secondary transfer is carried out by another shorter, made in the form of a vehicle belt (Fig. 13). Toner moves on paper under the action of electrostatic forces, i.e. Due to the difference in the potentials of toner powder (negative) and the border of the secondary transfer, which is supplied with a positive offset voltage. Since the secondary transfer is carried out only after four revolutions of the transfer drum, the Corrupton vehicle must submit paper only when all colors are applied, i.e. During the fourth turnover, and up to this point in time the belt should be in this position so that the paper does not touch the transfer drum.

Thus, the transport belt during the creation of the image is lowered down, and does not come into contact with the transfer drum, and at the time of the secondary transfer raised up and concerns this drum. The movement of the Corrupton vehicle is carried out by an eccentric cam, which is driven by an electric coupling by a microcontroller (Fig.14).

With secondary transfer, a sheet of paper can be attracted to the surface of the transfer drum due to the difference in electrostatic potentials. This can cause the papers to screw the paper on the drum, and, accordingly, to the paper jam. To prevent such a phenomenon in the printer, there is a system of separating paper and withdrawing static potential from it. The system is a huror, which is supplied by an alternating voltage of a sinusoidal shape with a positive constant component. The location of the border relative to the paper and the transfer drum is shown in Fig. 15.

At the stage of secondary transfer, some toner particles are not transferred to paper, but remain on the surface of the drum. To make these particles do not interfere with the creation of the next sheet and did not distort images, it is necessary to clean the transfer drum and remove the toner residues. Cleaning the transfer drum is a rather complicated process. For this procedure, a special cleaning roller, a photoraban cleaner and a photobaban cleaning unit are activated. The cleaning of the transfer drift should be carried out not constantly, but only after the secondary transfer, i.e. The cleaning system should be controlled similarly to the shipping. As long as the image is created, the cleaning system is not active, and when the toner is started on paper - turns on. The first phase of purification is the reload of the residual toner powder, i.e. His potential changes with a negative on a positive one. To do this, the cleaning roller is applied, to which a variable sinusoidal voltage with a positive constant component is supplied. This video is pressed against the surface of the phototrabane during the cleaning period, and during the creation of the image it is folded. The roller is controlled by an eccentric cam, which in turn is activated by the solenoid (Fig.16).

After that, a positively charged toner is transferred to a photorabank, on which there is still a negative offset voltage. And already from the surface of the photobrabam, the toner is considered a cleansing rocket of the photobaban cleaning unit (Fig.17).

Creating a full color image with toner fixation on paper with temperature and pressure. The sheet of paper passes between the two rollers of the fixation block (stove), heated to the temperature of about 200 ºС, the toner is melted and pressed into the surface of the paper. To prevent toner sticking to the stove on the heating shaft, a negative bias voltage is supplied, as a result of which the negative toner powder remains on paper, and not on the Teflon shaft.

We reviewed the principle of operation of only one printer of one company. Other manufacturers can also use other principles of image formation and other technical solutions when building printers, however, all these solutions will be very close to what they have been considered earlier.