Most modern printers are divided into laser and inkjet printers. Moreover, thanks to progress, the latter are gradually leaving the market of "household office equipment", remaining specialized. In offices, homes, and even some print centers, laser printers are the most common.

In domestic use, the main difference between inkjet printers and laser printers lies primarily in the high cost-effectiveness of the latter. Ink consumption is practically minimal - one cartridge is enough for several thousand sheets with a fairly high density of ink. In addition, laser printers work very quickly and do not require special service maintenance.

Contrary to popular belief, laser printers do not "burn" characters into paper. A special toner is used to apply the image. It is he who sticks to the paper sheet, leaving symbols or pictures. By the way, because of this feature of the technology, color laser printers are practically never found, unlike monochrome (black and white).

The main functional units of a laser printer

The design of any laser printer, regardless of the specific model, manufacturer and capabilities, includes several main functional units:

• drum. It is on it that the toner is applied by means of electrostatic attraction and repulsion according to Coulomb's law;
• squeegee. It is designed to clean the drum of toner residue before applying a new one;
• coronator. This device is designed to electrostatically charge the drum;
• laser and mirror system. Being a source of coherent electromagnetic radiation, it discharges the drum pointwise;
• magnetic shaft. Toner is fixed on it for subsequent transfer to the surface of the drum;
• stove. It is designed to bake the toner left on the paper. Therefore, the sheets that come out of the laser printer have a fairly high temperature;
• control model (controller)- a microprocessor system that controls all this equipment.

Both color and monochrome laser printers are based on these functional units. Only the system and possibilities change. For example, color laser printers have four drums - for each of the fundamental colors (red, yellow, blue and black) - and a so-called transfer belt, which is designed to transfer the image formed by the corresponding toners to paper.

The principle of operation of a laser printer

The principle of operation of a laser printer in an abbreviated description is quite simple. The complete differs from one model to another, however, some fundamental elements are present in each case:

1. The drum is being cleaned. The doctor blade removes toner adhering to its surface, but not used in the previous printing cycle;
2. The coronator charges the surface of the drum. Either positive ions appear on it, or the number of negative electrons increases. This is intended to give rise to Coulomb forces.
3. A laser controlled by a rotating mirror partially discharges the surface of the drum. The toner itself is negatively or positively charged. Therefore, it repels from the charged areas of the drum area and is attracted to the discharged ones. Again, this is due to the action of Coulomb forces.
4. Toner powder is transferred from the surface of the magnetic roller to the drum.
5. From the surface of the drum, the toner adhered to it is transferred to the paper sheet.
6. The paper is sent to the “oven”, which most often consists of a heating element in the form of a halogen lamp and a pressure roller. The toner is fixed by melting under the action of high temperature and due to pressure from the shaft fixed on the spring.

If 4 separate drums and the same number of magnetic rollers are installed in color laser printers, however, the toner is not applied directly to the paper itself, but to the transfer ribbon. All four shades are first applied to it. The transfer ribbon is then rolled across the paper, and the multi-colored image is placed on the sheet. The toner is then baked and fixed.

Fundamental non-technological differences between laser and inkjet printers

Laser printers have been more popular than inkjet printers lately. If we abstract from technological differences, then they have the following advantages:

• economy. A laser printer cartridge lasts for several thousand sheets of high coverage paper.
• refueling option. Laser printer cartridges can be refilled with toner as needed without the risk of compromising their functionality. You can even carry out this operation on your own, but you should be careful, because the coloring pigment is negatively or positively charged and quickly sticks to skin, clothes and other surfaces under the influence of Coulomb forces. Inkjet printer cartridges in most cases cannot be refilled, as this leads to a violation of their tightness. For some models of this type of equipment, continuous ink supply systems can be used, but this is considered an unauthorized modification and will void the warranty agreement.
• high speed. Most laser printers can print up to 10 text pages per minute. Some work even faster.
• no need for weekly printing. The toner used in laser printers does not dry out or stick together. Therefore, periodically "chasing the print" to prevent head clogging is not necessary. Actually, there is no head in laser printers.
• print durability. Images and text on paper obtained using such office equipment do not fade or disappear over time under the influence of high humidity.
• high image resolution. Color laser printers provide print resolutions up to 9600 x 1200 dpi.

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

• high cost. On average, a laser printer in a complete set "from the factory" - that is, with incomplete cartridges - costs several times more than a similar inkjet. For monochrome, this is a 2-3-fold increase in price, for color - 10-fold and higher.
• high cost of cartridges and toner. Consumables for laser printers cost 2-3 times more than for inkjet printers. However, it is worth considering that their usage limit is also 2-3 times higher.
• bulkiness. Laser printers are usually several times larger than inkjet printers. This is also due to the complexity of the design. As a result, they require a separate place for installation.
• the need to warm up before work and the risk of overheating after prolonged typing. Despite the fact that the design of the “stove” includes a special thermoelement that does not allow the temperature to reach a critical level, in some cases it may fail or work inadequately. After that, the device overheats with the risk of system problems.
• little environmental friendliness. During operation, such devices release into the air some harmful compounds, dust, and also emit infrared and ultraviolet radiation.
• high resource intensity. Due to the presence of "gluttonous" in relation to the current elements, laser printers consume more electricity. Moreover, peak power can be so high that such office equipment will not work from household or office UPSs.
• the impossibility of stable repetition of full-color images due to the uncontrolled action of electromagnetic fields.

Thus, laser printers have both advantages and disadvantages compared to inkjet printers. However, in some use cases, they prove to be significantly more optimal or useful than their counterparts.

Today I want to talk about device and principle of operation of a laser printer. Everyone is familiar with this device, but few people know about the principle of its operation and the causes of its malfunctions. In this article I will try to clearly talk about the principle of operation of "laser printers", and in subsequent articles about malfunctions of laser printers, about the reason for their appearance, and about how to eliminate them.

Laser printer device

At the heart of any modern laser printer is a photoelectricprinciple xerography. Based on this method, all laser printers structurally consist of three main parts (assemblies):

- Laser sanitizing unit.

- Image transfer unit.

- Node for fixing the image.

The image transfer unit usually refers to the laser printer cartridge and charge transfer roller (Transferroller) in the printer itself. We will talk about the device of the “laser” cartridge later in more detail, and in this article we will consider only the principle of operation. It should also be noted that instead of laser scanning in some printers (mainly from OKІ» ) LED scanning is applied. It performs the functionseHowever, only the role of the laser is performed by LEDs.

For example, consider laser printer HP LaserJet 1200 (Fig. 1.). The model is quite successful and well-proven for its long service life, convenience and reliability.

We print on any material (mainly paper), and the paper feed unit is responsible for sending it to the “mouth” of the printer. As a rule, it is divided into two types that are structurally different from each other. Lower Tray Feeder, is called - Tray 1, and feeding mechanism from the top(bypass) - Tray 2. Despite the structural differences in their composition, they have (see Fig. 3):

- Pickup Roller- needed to pull paper into the printer,

- Block brake pad and separator needed to separate and pick up only one sheet of paper.

Directly involved in the formation of the image printer cartridge(Fig. 4) and laser scanning unit.

The cartridge for laser printers consists of three main elements (see Fig. 4):

Photocylinder,

precharge shaft,

magnetic shaft.

photo cylinder

photo cylinder(ORS- organicphotoconductivedrum), or also photoconductor, is an aluminum shaft coated with a thin layer of photosensitive material, which is additionally covered with a protective layer. Previously, photocylinders were made on the basis of selenium, so they were also called selenium shafts, are now made from photosensitive organic compounds, but their old name is still widely used.

Main property photocylinder– change the conductivity under the influence of light. What does it mean? If the photocylinder is given some kind of charge, then it will remain charged for quite a long time, however, if its surface is illuminated, then in places of illumination the conductivity of the photocoating increases sharply (resistance decreases), the charge "flows" from the surface of the photocylinder through the conductive inner layer in this place a neutrally charged region will appear.

Rice. 2 HP 1200 Laser Printer with cover removed.

The numbers indicate: 1 - Cartridge; 2 - Image transfer unit; 3 - Node for fixing the image (stove).

Rice. 3 Paper feed unitTray 2 , rear view s.

1 - Paper pickup roller; 2 - Braking pad (blue stripe) with a separator (not visible in the photo); 3 - Charge transfer roller (transferroller), transmitting paper static charge.

Rice. 4 Disassembled laser printer cartridge.

1- Photocylinder; 2- Precharge shaft; 3- Magnetic shaft.

Image overlay process.

Photo cylinder with pre-charge shaft (PCR) receives an initial charge (positive or negative). The amount of charge itself is determined by the print settings of the printer. After the photocylinder is charged, the laser beam passes over the surface of the rotating photocylinder, and the places where the photocylinder is illuminated become neutrally charged. These neutral areas correspond to the desired image.

The laser scanning unit consists of:

semiconductor laser with focusing lens,
- Rotating mirror on the motor,
- Forming lens groups,
- Mirrors.

Rice. 5 Laser scanning unit with cover removed.

1,2 - Semiconductor laser with focusing lens; 3- rotating mirror; 4- Forming lens group; 5- Mirror.

The drum has direct contact magnetic shaft m (Magneticroller), which supplies toner from the cartridge hopper to the photo cylinder.

The magnetic shaft is a hollow cylinder with a conductive coating, inside which a permanent magnet rod is inserted. The toner located in the hopper in the hopper is attracted to the magnetic shaft under the influence of the magnetic field of the core and an additionally applied charge, the value of which is also determined by the print settings of the printer. This determines the density of future printing. From the magnetic shaft, under the action of electrostatics, the toner is transferred to the image formed by the laser on the surface of the photocylinder, since it has an initial charge, it is attracted to the neutral regions of the photocylinder and repelled from equally charged ones. This is the image we need.

There are two main mechanisms for creating an image. Most printers (HP,Canon, Xerox) a toner with a positive charge is used, remaining only on the neutral surfaces of the photocylinder, that is, the laser illuminates only those areas where the image should be. The photo cylinder in this case is negatively charged. The second mechanism (used in printersEpson, Kyocera, Brother) is to use a negatively charged tuner, and the laser discharges areas of the photocylinder that should not have toner. The photo cylinder initially receives a positive charge and the negatively charged toner is attracted to the positively charged areas of the photo cylinder. Thus, in the first case, a finer transfer of details is obtained, and in the second, a denser and more uniform fill. Knowing these features, you can more accurately select a printer for solving your problems (printing text or printing sketches).

Before contact with the photo cylinder, the paper also receives a static charge (positive or negative), via the charge transfer roller (Transferroller). Under the influence of this static charge, the toner transfers from the photo of the cylinder to the paper during contact. Immediately after this, the static charge remover removes this charge from the paper, which eliminates the attraction of the paper to the photo cylinder.

Toner

Now we need to say a few words about the toner. Toner is a finely dispersed powder consisting of polymer balls coated with a layer of magnetic material. The composition of the color tuner also includes dyes. Each company in its models of printers, MFPs and copiers uses original toners that differ in dispersion, a magnetnawn and physical properties. Therefore, in no case should you refill cartridges with random toners, otherwise you can ruin your printer or MFP very quickly (verified by experience).

If, after passing the paper through the laser scanning unit, remove the paper from the printer, we will see an image that has already been formed, which can be easily destroyed by touch.

Image fixation unit or "stove"

In order for an image to become durable, it must be fix. Image freeze occurs with the help of additives that are part of the toner, having a certain melting point. The third main element of the laser printer is responsible for fixing the image (Fig. 6) - image fixation unit or "stove". From a physical point of view, fixation is carried out by pressing the molten toner into the paper structure and its subsequent solidification, which gives the image durability and good resistance to external influences.

Rice. 6 Image fixation unit or stove. Top view assembled, bottom with paper separator bar removed.

1 - Thermal film; 2 - Pressure shaft; 3 - Paper separator bar.

Rice. 7 Heating element and thermal film.

Structurally, the “stove” can consist of two shafts: the upper one, inside which there is a heating element, and the lower shaft, which is necessary for pressing the molten toner into the paper. In the HP 1200 printer under consideration, the “stove” consists of thermal films(Fig. 7) - a special flexible, heat-resistant material, inside of which there is a heating element, and a lower pressure roller, which presses the paper due to the support spring. Monitors the temperature of the thermal film temperature sensor(thermistor). Passing between the thermal film and the pressure roller, the paper heats up to approximately 200 ° C at the points of contact with the thermal film.˚ . At this temperature, the toner melts and in liquid form is pressed into the texture of the paper. So that the paper does not stick to the thermal film, there are paper separators at the exit from the oven.

Here's what we've looked at - How does a printer work. This knowledge will help us in the future to find out the causes of breakdowns and eliminate them. But in no case should you climb into the printer yourself if you are not sure that you can fix it, this will only make it worse. It is better not to save money, but to entrust this matter to professionals, because buying a new printer will cost you much more.

Laser printers have become indispensable attributes of office equipment. Such popularity is explained by the high speed and low cost of printing. To understand how this technique works, you should know the device and principle of operation of a laser printer. In fact, all the magic of the device is explained by simple design solutions.

Back in 1938, Chester Carlson patented a technology that transferred an image to paper using dry ink. The main engine of work was static electricity. Electrographic method(and it was he) became widespread in 1949, when the Xerox Corporation took it as the basis for the operation of its very first device. However, it took another decade of work to achieve logical perfection and complete automation of the process - only after that did the first Xerox appear, which became the prototype of modern laser printing devices.

First Xerox 9700 Laser Printer

The very first laser printer appeared only in 1977 (it was the Xerox 9700 model). Then printing was done at a speed of 120 pages per minute. This device was used exclusively in institutions and enterprises. But already in 1982, the first Canon desktop unit was released. Since that time, numerous brands have been involved in the development, which to this day offer more and more new options for desktop laser printing assistants. Each person who decides to use such a technique will be interested to learn more about the internal structure and principle of operation of such a unit.

What's inside

Despite the large assortment, the laser printer device of all models is similar. The work is based on photoelectric part of xerography, and the device itself is divided into the following blocks and nodes:

• laser scanning unit;
• a node that transfers the image;
• node for fixing the image.

The first block is presented lens and mirror system. It is here that a semiconductor type laser with a focusable lens is located. Next are mirrors and groups that can rotate, thereby forming an image. We pass to the node responsible for transferring the image: it contains the toner cartridge and roller carrying charge. Already in the cartridge alone, there are three main image-forming elements: a photo cylinder, a pre-charge roller and a magnetic roller (working in conjunction with the drum of the device). And here the possibility of a photocylinder to change its conductivity under the action of light that has fallen on it acquires great relevance. When the photo cylinder is charged, it retains it for a long time, but when illuminated, its resistance decreases, which leads to the fact that the charge begins to drain from its surface. This gives us the impression we need.

In general, there are two ways to create a picture.

Getting into the unit, immediately before the future contact with the photocylinder, the paper itself receives the corresponding charge. The transfer roller helps her with this. After the transfer, the static charge disappears with the help of a special neutralizer - this is how the paper ceases to be attracted to the photo cylinder.

How is the image captured? This is due to those additives that are in the toner. They have a specific melting point. Such a "stove" presses the molten toner powder into the paper, after which it quickly hardens and becomes durable.

Images printed on paper by a laser printer have excellent resistance to numerous external influences.

How the cartridge works

The defining link in the operation of a laser printer is the cartridge. It is a small bin with two compartments - for working toner and for already used material. There is also a light-sensitive drum (photocylinder) and mechanical gears for turning it.

The toner itself is a fine-dispenser powder, which consists of polymer balls - they are covered with a special layer of magnetic material. If we are talking about color toner, then it also contains dyes.

It is important to know that each manufacturer produces its own original toner - all of them have their own magneticness, dispersion and other properties.

That is why in no case should you refill cartridges with random toners - this can adversely affect its performance.

The process of making an impression

The appearance of an image or text on paper will consist of the following successive stages:

• drum charge;
• exposure;
• developing;
• transfer;
• fastening.

How does photocharge work? It is formed on the photodrum (where, as is already clear, the future image itself is born). To begin with, there is a supply of charge, which can be both negative and positive. This happens in one of the following ways.

1. used coronator, that is, a tungsten filament coated with carbon, gold and platinum inclusions. When a high voltage comes into play, a discharge is carried between this thread by a frame, which, accordingly, will create an electric field that transfers a charge to the photoconductor.
2. However, the use of filament led to problems with soiling and degradation of printed material over time. Works much better charge roller with similar features. He himself looks like a metal shaft, which is covered with conductive rubber or foam rubber. There is contact with the photocylinder - at this moment the roller transfers the charge. The voltage here is much lower, but the parts wear out much faster.

This is the work of illumination, as a result of which part of the photo cylinder becomes conductive and passes the charge through the metal base in the drum. And the exposed area becomes uncharged (or acquires a weak charge). At this stage, a still invisible image is formed.

Technically it works like this.

1. The laser beam falls on the surface of the mirror and is reflected onto the lens, which distributes it to the desired location on the drum.
2. So the system of lenses and mirrors forms a line along the photocylinder - the laser turns on and off, the charge either remains intact or is removed.
3. Line ended? The drum unit will rotate and the exposure will continue again.

development

In this process, it is important cartridge magnetic shaft, similar to a tube made of metal, inside of which there is a magnetic core. Part of the surface of the shaft is placed in the refill toner hopper. The magnet attracts the powder to the shaft, and it is carried out.

It is important to regulate the uniformity of the distribution of the powder layer - for this there is a special dosing blade. It passes only a thin layer of toner, throwing the rest back. If the blade is not installed correctly, black streaks may appear on the paper.

After that, the toner moves to the area between the magnetic roller and the photocylinder - here it will be attracted to the exposed areas, and repelled from the charged ones. So the image becomes more visible.

Transfer

In order for the image to appear already on paper, it comes into play transfer roller, in the metal core of which a positive charge is attracted - it is transferred to paper thanks to a special rubberized coating.

So, the particles break away from the drum and begin to move onto the page. But they are kept here so far only because of static stress. Figuratively speaking, the toner is simply poured where it is needed.

Dust and paper lint can get in with the toner, but they can be removed viper(with a special plate) and sent straight to the waste compartment on the hopper. After a full circle of the drum, the process is repeated.

To do this, the property of the toner to melt at high temperatures is used. Structurally, this is assisted by the following two shafts:

• at the top there is a heating element;
• at the bottom, melted toner is pressed into the paper.

Sometimes such a "stove" is thermal film- a special flexible and heat-resistant material with a heating component and a pressure roller. Its heating is controlled by a sensor. Just at the moment of passage between the film and the pressure part, the paper heats up to 200 degrees, which allows it to easily absorb the liquid toner.

Further cooling occurs naturally - laser printers usually do not require the installation of an additional cooling system. However, a special cleaner passes here again - usually its role is played by felt shaft.

Felt is usually impregnated with a special compound, which helps to lubricate the coating. Therefore, another name for such a shaft is oil.

How color laser printing works

But what about color printing? The laser device uses four of these basic colors - black, magenta, yellow and cyan. The principle of printing is the same as in the black and white case, however, the printer will first split the image into monochrome for each color. The successive transfer of each color by each cartridge begins, and as a result of the overlay, the desired result is obtained.

There are such technologies of color laser printing:

• multipass;
• single pass.

At multi-pass option an intermediate carrier comes into play - this is a shaft or tape that carries the toner. It works like this: 1 color is superimposed in 1 revolution, then another cartridge is fed to the right place, and the second one is placed on top of the first picture. Four passes are enough to form a complete picture - it will go to paper. But the device itself will work 4 times slower than its black and white counterpart.

How the printer works single pass technology? In this case, all four separately printing mechanisms have a common control - they are lined up in one line, each has its own laser unit with a portable roller. So the paper goes along the drum, sequentially collecting all four images of the cartridges. Only after this passage does the sheet go into the oven, where the picture is fixed.

The merits of laser printers have made them a favorite for document work, both in the office and at home. And information about the internal component of their work will help any user to notice shortcomings in time and contact the service department for technical support for the operation of the device.

In a printer based on laser printing technology, everything works by using static electricity. How it works? A laser beam hits the photoconductor in the cartridge and forms an image. At the next stage of image formation, the photoconductor comes into contact with the toner and at the point of contact, where the laser shone and changed the charge, the toner sticks. By the same principle, toner sticks to the paper from the photodrum, and then it is baked in the so-called “stove”. The paper comes out warm from the stove. Don't worry, it's already a little cold.

Learn more about the laser printer printing process

When the photosensitive drum rotates, a positive charge is formed on its surface, which is applied to the photo roller using a laser beam. The positive charge attracts the toner particles, which are negatively charged, and they adhere to the surface of the drum.

The sheet of paper is positively charged and passes under the rotating photo roller during the printing process. Negatively charged toner particles are transferred from the drum to the sheet of paper, thus the image is transferred to the paper. Further, the toner, which is on the paper, is fixed under the influence of heat.

Unlike printing on dot-matrix and inkjet printers, where the image is transferred to paper line by line, with laser printing, the text on an A4 sheet is formed in just 3 turns of the drum unit.

Laser printers are based on the printing system used in copiers. In copiers, a special lamp transfers the image from the copied sheet to the photosensitive surface of the drum in the form of an electrostatic charge. The photoconductor converts the optical image created by the light reflected from the copied image into its electrostatic equivalent, which attracts toner particles with the opposite charge to the surface of the drum.

However, the laser printer does not have the original image; instead, it has a matrix of 1s and 0s in its memory that transmits the image. In the case of black and white printing, 1 sends a signal to the microprocessor and a laser beam is directed to the photoconductor. When the beam touches the surface of the drum, a positive charge is formed in this place, and negatively charged toner particles will adhere to the drum in this very place. Accordingly, 0 does not transmit a signal and no charge appears on the surface of the drum, and later these areas will remain white on paper. How to get rid of white stripes when printing, read the article -

In domestic conditions, laser and inkjet printers are popular. The principle of printing such devices is fundamentally different, which cannot but affect the operational features. In some cases it is best to use laser products, while in others it is best to use inkjet products. However, to make the final choice in favor of a particular device is possible only after considering the scheme of work.

Working principle of inkjet printer

Still, at home, it is the inkjet printer that is most often used. The principle of printing it is to form an image using liquid ink. They are transferred to the media through special nozzles located on the head. The number of such holes depends on the model of the printer. Usually their number ranges from 16-64 pieces.

Since an inkjet printer prints using liquid ink, it dries on the head nozzles if it is left idle for a long time. This requires cleaning of the printing element, which involves the additional consumption of colorants.

Such devices consist of the following components:

• supporting structure;
• power supply;
• print head;
• cleaning system;
• devices for supplying media;
• control node.

A color image is obtained by superimposing three primary colors on top of each other. Black ink is often added to them, so that it is possible to use devices for the usual printing of texts and black-and-white drawings, saving on color inks.

Core Inkjet Printing Technologies

Different models may have their own advantages and disadvantages. The principle of printing representatives of inkjet printers may also differ slightly depending on the technology used. The difference lies only in the way the ink is transferred to the solid media.

1. The piezoelectric method involves the formation of ink dots on paper using special devices that are connected to the diaphragm. The electric field has a direct effect on the piezoelectric element, and it expands the tube to fill the capillary system. The main advantage lies in the flexible control of the droplet dimensions, which makes it possible to obtain high-quality images with high resolution.
2. The gas bubble method implies the presence of heating elements directly in the nozzles. Electricity is passed through them. During the heating process, gas bubbles are formed, which push the right portion of liquid ink through the holes. After the heater cools down, a fresh portion of the coloring matter enters through the nozzles. High quality is noted for detailed drawing of lines, but when printing solid areas, there may be slightly blurry places.
3. The thermal jet method, as in the previous case, involves the use of a heating element. However, a special mechanism is used with it, which allows for faster injection of colorants. As a result, device performance increases. The color palette of the resulting image differs in contrast.

The inks used may vary. Water-based ink contains a soluble dye and certain additives to adjust the viscosity. Their advantage lies in their low cost. Pigment inks are UV and moisture resistant. The print quality in this case is less dependent on the media.

Using continuous ink supply

With the principle of printing an inkjet printer, everything became clear. Special cartridges are used to store dyes. However, there is a special system that allows you to continuously supply ink in order to save money. In this case, the capsule reservoirs are installed directly on the print head.

The system is a set of containers connected by a silicone cable, through which ink is supplied from donors to the main unit. Thanks to this device, the constant presence of the original dyes in the print head is achieved. Many large format office fixtures have a built-in ink system that cannot be seen from the outside.

The principle of operation of the laser device

A completely different branch of the development of printing devices is laser technology, which can be used to achieve high-quality deposition of colorants on paper. The formation of characters and images occurs due to the beam illumination of the device elements with photosensitivity. The resulting copies with text or graphic information are resistant to fading and abrasion.

Inkjet and laser printers have completely different printing principles. Toners act as colorants, which can be transferred to a solid carrier in three ways.

1. Using a two-component development system. The dye particles needed to be transferred to a special photosensitive drum cannot be fixed on a magnetic roller without a special magnetic carrier charged by agitation.
2. With the use of one-component toner without additional impurities. Particles of matter in this case are endowed with magnetic properties. In some devices, electrostatic application can be carried out. With this option, the toner does not require magnetization.
3. Using a two-component dye, mixed at the factory.

Unlike an inkjet printer, the principle of printing a laser analog is based on building an image using the photographic method. The laser beam hits a special shaft, the surface of which is electrified due to impact ionization of the internal air.

Design of laser devices

Laser printers succeed in obtaining high-quality printing due to technological features. They include the following elements.

1. Photodrum, which is a cylinder made of aluminum. It is treated with a photosensitive material that tends to change electrical resistance in the presence of lighting.
2. The magnetic roller is used to transfer the toner from the reservoir directly to the drum or developing roller installed in some models of modern printers.
3. The doctor blade acts as a cleaning blade. With its help, excess coloring matter is removed from the screen roller. It can be made of plastic, steel or fiberglass.
4. The waste toner hopper is made in the form of a container. This compartment may be separate from the cartridge or together with it. The filling speed of such a tank depends on the quality of the toner.
5. The laser unit is designed to create an invisible image on the surface of the photoconductor by highlighting specific areas. The intensity of the beam can vary significantly.
6. The primary charge roller is made in the form of a metal rod covered with a layer of rubber. This element allows you to ensure the uniformity of the negative charge.
7. The transfer tape is necessary for applying an intermediate result from color cartridges.
8. The development unit allows you to transfer the toner directly onto the electrostatic image created on the surface of the photoconductive element.

Laser printing process

Not everyone fully understands the principle of printing laser printers from computer science courses. Inkjet devices operate according to a simplified scheme, so there are no special questions about them. How does the laser printing process work?

1. First, the photoconductive roller is charged. An electric charge is evenly distributed over its surface by rotating the roller. The rotating rod system reduces voltage and reduces the amount of ozone produced.
2. A laser scan is performed. At this moment, the charged surface of the shaft passes under the light beam. The laser hits only those places where the coloring matter will be applied in the future.
3. The toner is applied. A roller that has a negative charge transfers it to the toner. The dye from the hopper is attracted directly to the magnetic shaft, after which it comes into contact with the photoconductive element in those areas where the negative charge remains.
4. The transfer roller in contact with the solid carrier is no longer negatively charged but positively charged. Particles of the coloring matter fall on the surface of the paper due to electrostatic action.
5. The toner distributed over the carrier is fixed by heat and pressure. The thermal chamber consists of two shafts between which the paper moves. The temperature is controlled by a special sensor. The dye is melted and incorporated into the texture of the paper.

comparison table

It is suggested to look at the table to compare the properties of inkjet and laser printers, which print principle is very different.

Having briefly considered the principle of printing an inkjet printer, one cannot fail to note the features of operation.

1. It is not recommended to use the device less than once a week to avoid ink drying out.
2. It is necessary to purchase high quality dyes, otherwise the head can quickly become clogged.
3. The correct paper should be used and should be marked as suitable for inkjet printing.
4. It is required to keep the product clean, as dust leads to wear of moving parts.

Features of working with laser devices

The main advantage of laser printers is the absence of the need for regular operation. It can even be used once a month. This will not affect the quality of work or wear of parts. However, you must use only original toner cartridges, otherwise there is a high risk of damage to the device. In addition, third-party supplies may simply not work.

Before purchasing a device with a lot of positive reviews, you need to find out additional information about the cost:

• Supplies;
• wear parts;
• one page printout.

Sometimes it turns out that it is easier to purchase a new device than to replace any parts.

Final part

Having briefly considered the principle of printing inkjet and laser printers, we can draw certain conclusions about the acquisition of certain devices. However, the final choice will depend on what goals are pursued during operation. For printing large volumes of text information, it is more profitable to buy laser devices. If you need to get high-quality photos, then it is better to give preference to inkjet counterparts.