Laser and inkjet printer: printing principle. How a laser printer works and works How laser printing works

Many people believe that a laser printer is so named because it burns images onto paper with a laser. However, a laser alone is not enough to get a high-quality print.

The most important element laser printer consider the photoconductor. It is a cylinder coated with a photosensitive layer. Another necessary component of toner is coloring powder. Its particles are fused into a sheet of paper, leaving the desired image on it.

The image drum and toner hopper are most often part of one solid cartridge, which in addition has many other important parts - charging and developing rollers, a cleaning blade and a waste toner hopper.

Now let’s look at how this all happens in more detail.

Printer operation steps

The electronic document is sent for printing. In this moment printed circuit board processes it, and the laser sends digital pulses to the cartridge. By charging the photodrum with negative particles, the laser transfers the image or text to be printed onto it.

When the laser beam hits the drum, it removes the charge and uncharged zones remain on its surface. Each particle of toner is negatively charged and when in contact with the photodrum, the toner adheres to uncharged fragments under the influence of static electricity. This is called image development.

A special roller with a positive charge presses the sheet of paper against the photodrum. Because oppositely charged particles attract, the toner sticks to the paper.

Next, the paper with toner is heated to a temperature of about 200 degrees using a thermal shaft of the so-called oven. Thanks to this, the toner expands and the image is securely fixed on the paper. Therefore, documents freshly printed on a laser printer are always warm.

At the last stage, the charge is removed from the photodrum and it is cleaned of the remaining toner, for which a cleaning blade and waste toner hopper are used.

This is how the printing process works. The laser paints a future image with charged particles. The photodrum catches and transfers the ink powder to the paper. The toner sticks to the paper due to static electricity and becomes fused to it.

Copiers work on the same principle.

Advantages of a laser printer

It is believed that the printing speed of a laser printer is higher than that of an inkjet printer. On average this is 27-28 prints per minute. Therefore, they are used to print a large number of documents.

The device does not make much noise during operation. The print quality is very high at a low cost per print, which is achieved due to the low consumption and price of toner. The cost of most laser printer models is also quite affordable.

For many years there has been controversy over whether laser printers are harmful to health. Particles of toner used for laser printing, are so small that they easily penetrate the human body, settle and accumulate in the respiratory tract. With constant contact with toner for 15-20 years, headaches, asthma and other diseases may develop.

However, printer manufacturers assure that there is no harm from using the printer every day. Production technologies are constantly being improved, and cartridges are tested in laboratories.

Danger can only arise if you try to open and refill the cartridge yourself. Toner particles can get into the lungs and are very difficult to remove from the body, so it is better to entrust refilling of the printer to specialists.

The speed, service life and print quality of laser printers are truly excellent. This device is indispensable in the work and everyday life of many users and is not as whimsical as capricious inkjet printers, who often have problems with printing when refilling.

If you still did not get the most successful model of a laser printer and you did not use it much, then do not despair. KupimToner buys new printers from different brands, as well as components for them, offering a decent price.

Today it is difficult to imagine life without printing devices. From time to time it is simply necessary to transfer information to paper. Schoolchildren need to print out reports, students need to print out diplomas and coursework, and office employees need to print out documents and contracts.

Working principle of an inkjet printer

First of all, let's look at how it works jet printer. It’s worth mentioning right away that in terms of print quality it lags slightly behind laser. However, the cost of an inkjet printer is significantly lower. This type The printer is perfect for home use. It is easy to handle and easy to maintain.
If we talk about the operating principle of laser and inkjet printers, they are radically different. The main difference is the ink supply technology, as well as the hardware design. Let's first discuss how an inkjet printer works.

The operating principle of this printing device is as follows: an image is formed on a special matrix, after which it is printed on a canvas using liquid ink. There is another type of inkjet printers that have cartridges. Cartridges are installed in a special block. In this design, ink is transferred to the print matrix using the print head. After this, the matrix transfers the image onto paper.

Storing ink and applying it to the canvas

There are several ways to apply ink to canvas:

— gas bubble method;
— piezoelectric method;
— drop-on-demand method.

The piezoelectric method involves the creation of ink dots on the canvas using a piezoelectric element. The tube opens and contracts again, preventing excess ink drops from falling. The gas bubble method is also known as the injected bubble method. They leave an imprint on the canvas due to high temperatures. The nozzle of each printing matrix has a heating element. It takes a fraction of a second to heat up such an element. After heating, the resulting bubbles are transferred to the canvas through nozzles.

The drop-on-demand method also uses gas bubbles. However, this is a more optimized method. Print speed and quality have increased significantly.

Ink in an inkjet printer is typically stored in two ways. The first method involves the presence of a separate reservoir from which ink is supplied to the print head. In the second method, a special cartridge is used to store ink, which is located in the print head. To replace the cartridge, you will have to change the print head itself.

Using Inkjet Printers

Inkjet printers have gained particular popularity due to the fact that these devices have the ability to print in color. An image in color printing is created by superimposing basic tones with varying degrees of saturation on top of each other. The basic set of colors is also known by the abbreviation CMYK. It includes the following colors: black, cyan, purple and yellow. Initially, a set of three colors was used. It included all the colors listed above except black. But even when applying cyan, yellow and magenta colors at 100% saturation, it was still not possible to achieve black, the result was either gray or brown. For this reason, it was decided to add black ink to the main set.

Inkjet printer: operating features

The main indicators of printer performance are usually considered to be print speed, noise characteristics, durability and print quality. Let's consider the performance qualities of an inkjet printer.

The operating principle of such a printer has already been discussed above. Ink is supplied to paper through special printers. An inkjet printer operates very quietly, unlike, for example, needle printers, in which ink is applied through a mechanical impact process. You will not hear the inkjet printer printing; you can only hear the noise of the mechanism that moves the print heads. If speak about noise characteristics inkjet printers in quantitative terms, then during operation of such a device the noise level does not exceed 40 decibels.

Now let's talk about printing speed. An inkjet printer prints much faster than a pin printer. However, the quality of printing directly depends on such an indicator as speed. In this sense, the faster the print speed, the worse the quality. If you select High Quality Print mode, the process will slow down significantly. The paint on the canvas will be applied carefully. This printer prints at an average speed of 3 to 5 pages per minute. In modern printing devices, this figure has been increased to 9 pages per minute. Color images will take a little longer to print.

One of the main advantages of an inkjet printer is the font. In terms of the quality of font display, an inkjet printer can be compared, perhaps, only with a laser one. You can improve print quality by using good paper. The main thing is to choose paper that can quickly absorb moisture. High image quality can be achieved using paper with a density of 60 to 135 g/m2. Copier paper has proven itself well. Its density is 80 g/m2. To speed up the drying process of ink, some printing devices have a paper heating function. Despite the completely different operating principles of inkjet and laser printers, when using these devices it is possible to achieve the same quality.

Printing paper

An inkjet printer, unfortunately, is not suitable for printing on roll media. It is also not intended for making copies: you will have to use multiple printing.

Disadvantages of an inkjet printer

As mentioned earlier, inkjet printers print using a matrix. An image when printed on an inkjet printer is formed from dots. The most important and valuable element in the entire device is the print head. To reduce the size of the device, many companies integrate the print head into the cartridge. Inkjet and laser printers differ in their printing principles. The disadvantages of inkjet printers include the following:

1. Low printing speed;
2. Ink dries out after prolonged inactivity
3. High cost and short resource of consumables

Advantages of inkjet printers

1. Optimal ratio price/quality. When choosing a printing device, many users are most attracted by the price of this type of printer.
2. The printer has fairly modest dimensions. This makes it possible to mark it even in a small office or office. This will not create any inconvenience for the user.
3. Possibility to refill cartridges yourself. You can simply buy ink and read in the user manual how to refill it correctly.
4. Availability of the system continuous feed ink. This system will significantly reduce printing costs for large volumes.
5. High quality printing of images and photos
6. Big choice Print media used

Laser printer

A laser printer today means a special type of printing equipment designed for applying text or images to paper. This type of equipment has a very unusual history. The principle of operation of a laser printing device began to be discussed only in 1969. Scientific research was carried out over several years.

To improve the operating principle of this device, many methods have been proposed. The world's first copying machine using a laser beam to create a print appeared in 1978. This device It was huge in size, and its cost was off the charts. Some time later, Canon took up this development.

The first desktop laser printer appeared in 1979. This led to other companies beginning to optimize and promote new models of laser printers. The principle of printing itself has not changed. Prints obtained using a laser printer have high performance. They are not afraid of fading or erasing, they are not afraid of moisture. Images produced using a laser printer are highly durable and of high quality.

How a laser printer works

Let us briefly describe the operating principle of a laser printer. An image when printed on a laser printer is applied in several stages. First, a special powder called toner melts under the influence of temperature. It sticks to the paper. After this, the unused toner is removed from the drum with a special scraper and moved to the waste storage tank. The surface of the drum is polarized by a corona generator. An image is formed on the surface of the drum. The drum then moves along the surface of the magnetic roller, which contains the toner. Toner sticks to charged areas of the drum. The drum then comes into contact with the paper and leaves toner on it. Then the paper is rolled through a special oven, in which the powder melts under high temperature and sticks to the paper.

Color laser printer

The process of printing on a color printer differs from black and white by using several shades. By mixing these shades in a certain ratio, you can create primary colors. Typically, laser printers have their own compartment for each color. This is their main difference. Printing color images on such a printer occurs in several stages. First, the image is analyzed, after which the charge distribution is formed. Next, the same sequence of operations is carried out as for black and white printing: a sheet of toner is passed through an oven, where the powder melts and sets with the paper.

Advantages of laser printers

1. High speed print
2. Image endurance and durability
3. Low cost
4. High quality

Disadvantages of laser printers

1. During operation, ozone is released. Print on a laser printer only in a well-ventilated area
2. Bulky
3. High power consumption
4. High price

Conclusion

Having analyzed the operating principle and main characteristics of inkjet and laser printers, we can say that for home use The first type of device is more suitable. They are affordable and small in size. Laser printers are more suitable for offices where large quantities of documents need to be printed.

Laser printers provide more high quality than inkjet printers. The most famous companies developing laser printers are Hewlett-Packard and Lexmark.

The operating principle of a laser printer is based on the method of dry electrostatic image transfer, invented by C.F. Carlson in 1939 and also implemented in copying machines. The functional diagram of the laser printer is shown in Fig. 5.6. The main design element is rotating drum, serving as an intermediate medium with which the image is transferred to paper.

Rice. 5.6. Functional diagram of a laser printer

Drum is a cylinder coated with a thin film of light-conducting semiconductor. Typically, zinc oxide or selenium is used as such a semiconductor. The static charge is evenly distributed over the surface of the drum. This is achieved by a fine wire or mesh called a corona wire, or corotron. A high voltage is applied to this wire, causing a glowing ionized area called a corona to appear around it.

Laser, controlled by a microcontroller, generates a thin beam of light that is reflected from a rotating mirror. The image is scanned in the same way as in a television kinescope: by moving the beam along the line and frame. With the help of a rotating mirror, the beam slides along the cylinder, and its brightness changes abruptly: from complete light to complete darkness, and the cylinder is charged in the same abrupt manner (pointwise). This ray, reaching the drum, changes it electric charge at the point of contact. The size of the charged area depends on the focusing of the laser beam. The beam is focused using a lens. A sign of good focusing is the presence of clear edges and corners in the image. For some types of printers, during the charging process, the potential of the drum surface decreases from 900 to 200 V. Thus, a hidden copy of the image appears in the form of an electrostatic relief on the drum, the intermediate medium.

At the next stage, it is applied to the phototypesetting drum. toner- paint, which is the smallest particles. Under the influence of a static charge, particles are easily attracted to the surface of the drum at exposed points and form an image in the form of a dye relief.

Paper is pulled from the feed tray and moved to the drum using a roller system. Just before the drum, the corotone imparts a static charge to the paper. The paper then comes into contact with the drum and, thanks to its charge, attracts the toner particles previously applied to the drum.

To fix the toner, the paper is passed between two rollers at a temperature of about 180 "C. After the printing process is completed, the drum is completely discharged, cleaned of adhering excess particles to carry out a new printing process. A laser printer is page by page, i.e. it forms a full page for printing.

The process of operation of a laser printer, from the moment it receives a command from the computer to the output of the printed sheet, can be divided into several interconnected stages, during which such functional components of the printer as the central processor are involved; scan processor; mirror motor control board; beam brightness amplifier; temperature control unit; sheet feed control unit; paper feed control board; interface board; power unit; control panel buttons and indication board; additional RAM expansion cards. Essentially, a laser printer functions like a computer: the same central processing unit, which houses the main interconnection and control functions; RAM, where data and fonts are located, interface boards and a control panel board, which communicates the printer with other devices, a printing unit, which outputs information onto a sheet of paper.

Color laser printers are beginning to actively conquer the printing market. If just a few years ago color laser printing was something unattainable for most organizations, and even more so for individual citizens, now a very wide range of users can afford to buy a color laser printer. The rapidly growing fleet of color laser printers is leading to growing interest in them from technical support services.

Principles of color printing

In printers, as in printing, it is used to create color images. subtractive color model, and not additive, as in monitors and scanners, in which any color and shade is obtained by mixing three primary colors - R(red), G(green), B(blue). The subtractive color separation model is so called because in order to form any shade, it is necessary to subtract “extra” components from the white color. In printing devices, to obtain any shade, the following are used as primary colors: Cyan(blue, turquoise), Magenta(purple), Yellow(yellow). This color model is called CMY by the first letters of the primary colors.

In the subtractive model, when two or more colors are mixed, complementary colors are created by absorbing some light waves and reflecting others. Blue paint, for example, absorbs red and reflects green and blue; purple paint absorbs green color and reflects red and blue; and yellow paint absorbs blue and reflects red and green. By mixing the main components of the subtractive model, different colors can be obtained, which are described below:

Blue + Yellow = Green

Magenta + Yellow = Red

Magenta + Cyan = Blue

Magenta + Cyan + Yellow = Black

It is worth noting that to obtain black it is necessary to mix all three components, i.e. cyan, magenta and yellow, but getting high-quality black in this way is almost impossible. The resulting color will not be black, but rather a dirty gray. To eliminate this drawback, one more color is added to the three main colors - black. This extended color model is called CMYK(C yan- M agenta- Y ellow-black K – cyan-magenta-yellow-black). The introduction of black color can significantly improve the quality of color rendering.

HP Color LaserJet 8500 Printer

After we have discussed the general principles of the construction and operation of color laser printers, it is worth familiarizing yourself in more detail with their structure, mechanisms, modules and blocks. This is best done using the example of a printer. As an example, let's take the Hewlett-Packard Color LaserJet 8500 printer.

Its main characteristics are:
- resolution: 600 DPI;
- print speed in “color” mode: 6 ppm;
- print speed in “black and white” mode: 24 ppm.

The main components of the printer and their relative positions are shown in Fig. 5.

Image formation begins with residual potentials being removed (neutralized) from the surface of the photodrum. This is done so that the subsequent charge of the photodrum is more uniform, i.e. Before charging it is completely discharged. Removal of residual potentials is carried out by illuminating the entire surface of the drum with a special preliminary (conditioning) exposure lamp, which is a line of LEDs (Fig. 7).

Next, a high-voltage (up to -600V) negative potential is created on the surface of the photodrum. The drum is charged with a corotron in the form of a roller made of conductive rubber (Fig. 8). The corotron is supplied with a sinusoidal alternating voltage with a negative DC component. The alternating component (AC) ensures uniform distribution of charges on the surface, and the constant component (DC) charges the drum. The DC level can be adjusted by changing the print density (toner density), which is done using the printer driver or through adjustments through the control panel. An increase in negative potential leads to a decrease in density, i.e. to a lighter image, while decreasing the potential – on the contrary, to a denser (darker) image. The photodrum (its internal metal base) must be “grounded”.

After all this, a laser beam creates an image on the surface of the photodrum in the form of charged and uncharged areas. The laser light beam, hitting the surface of the drum, discharges this area. The laser illuminates those areas of the drum where the toner should be. Those areas that should be white are not illuminated by the laser, and a high negative potential remains on them. The laser beam moves across the surface of the drum using a rotating hexagonal mirror located in the laser assembly. The image on the drum is called a latent electrographic image, because it is represented as invisible electrostatic potentials.

The latent electrographic image becomes visible after passing through the developing unit. The black toner developing module is stationary and is in constant contact with the photodrum (Fig. 9).

The color developing module is a carousel mechanism with alternate supply of “color” cartridges to the surface of the drum (Fig. 10). Black toner powder is single-component magnetic, while colored toner powders are single-component but non-magnetic. Any toner powder is charged to a negative potential due to friction against the surface of the developing roller and the dosing squeegee. Due to the potential difference and the Coulomb interaction of charges, negatively charged toner particles are attracted to those areas of the photodrum that are discharged by the laser and are repelled from areas with a high negative potential, i.e. from those that were not illuminated by the laser. At any given time, only one color of toner is developed. During development, a bias voltage is applied to the developing roller, which causes toner to transfer from the developing roller to the drum. This voltage is a rectangular alternating voltage with a negative DC component. The DC level can be adjusted as the toner density changes. After the development process is completed, the image on the drum becomes visible and must be transferred to the transfer drum.

Therefore, the next step in creating an image is to transfer the developed image to the transfer drum. This stage is called the primary transfer stage. The transfer of toner from one drum to another occurs due to an electrostatic potential difference, i.e. Negatively charged toner particles should be attracted to the positive potential on the surface of the transfer drum. To do this, a positive bias voltage is applied to the surface of the transfer drum. direct current from a special power source, as a result of which the entire surface of this drum has a positive potential. When printing full color, the bias voltage on the transfer drum must constantly increase because After each pass, the amount of negatively charged toner on the drum increases. And in order for the toner to transfer and lay on top of the existing toner, the transfer voltage increases with each new color. This imaging stage is shown in Fig. 11.

During the transfer of toner to the transfer drum, some particles of toner may remain on the surface of the image drum and must be removed to avoid distorting the subsequent image. To remove residual toner, the printer has a drum cleaning unit (see Figure 17). This module contains a special shaft - a brush for removing the charge from the toner and the photodrum - this weakens the force of attraction of the toner to the photodrum. There is also a traditional cleaning squeegee that scrapes the toner into a special hopper where it is stored until the cleaning module is replaced or cleaned.

Next, the photodrum is charged again (after preliminary discharge), and the process is repeated until the image of the corresponding color is completely formed on the transfer drum. Therefore, the size of the transfer drum must fully correspond to the print format, i.e. in this printer model, the circumference of this drum corresponds to the length of an A3 sheet (420 mm). After applying toner of one color, the image formation process is completely repeated with the only difference being that a developing unit of a different color is used. To use another developing unit, the carousel mechanism rotates at a given angle and brings the “new” developing shaft to the surface of the photodrum. Thus, when forming a full-color image consisting of four color components, the transfer drum is rotated four times, and at each rotation a toner of a different color is added to the existing toner. In this case, the powder is applied first yellow color, then purple, then blue, and lastly black powder is applied. As a result, a full-color visible image is created on the transfer drum, consisting of particles of four multi-colored toner powders.

After the toner powder lands on the surface of the transfer drum, it passes through the additional charge unit. This block (Fig. 12) is a wire coroton, to which a sinusoidal alternating voltage (AC) with a negative direct component (DC) is supplied. With this voltage, the toner powder is additionally charged, i.e. its negative potential becomes higher, which will contribute to more efficient transfer of toner to paper. In addition, the additional voltage reduces the positive potential of the transfer drum, which helps ensure that the toner is positioned correctly on the transfer drum and prevents the toner from moving. The result is accurate reproduction of color shades. The additional charge voltage 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 yellow toner powder, the additional charge voltage is set to a minimum value, and after applying each new color, this voltage increases. Maximum voltage additional charge is supplied while black toner is being applied.

Next, the full-color visible image from the transfer drum must be transferred to paper. This transfer process is called secondary transfer. Secondary transfer is carried out by another corotron, made in the form of a transport belt (Fig. 13). The toner is moved onto the paper by electrostatic forces, i.e. due to the potential difference between the toner powder (negative) and the secondary transfer corotron, to which a positive bias voltage is applied. Since secondary transfer occurs only after four rotations of the transfer drum, the corotron transfer belt must feed the paper only when all colors have been applied, i.e. during the fourth revolution, and until this point in time, the belt should be in such a position that the paper does not touch the transfer drum.

Thus, during image creation, the transport belt is lowered down and does not come into contact with the transfer drum, but at the time of secondary transfer it is raised up and touches this drum. The corotron transport belt is moved by an eccentric cam, which is driven by an electric clutch upon command from the microcontroller (Fig. 14).

During secondary transfer, a sheet of paper may be attracted to the surface of the transfer drum due to the difference in electrostatic potential. This may cause the sheet of paper to wrap around the drum, resulting in a paper jam. To prevent this phenomenon, the printer has a system for separating paper and removing static potential from it. The system is a corotron to which an alternating sinusoidal voltage with a positive constant component is supplied. The location of the corotron relative to the paper and transfer drum is shown in Fig. 15.

During the secondary transfer stage, some toner particles are not transferred to the paper, but remain on the surface of the drum. To prevent these particles from interfering with the creation of the next sheet and distorting the image, it is necessary to clean the transfer drum and remove any remaining toner. Cleaning the transfer drum is a fairly complex process. This procedure uses a special cleaning roller, image drum, and image drum cleaning unit. The transfer drum should not be cleaned continuously, but only after the secondary transfer, i.e. The cleaning system should be controlled similarly to the transfer corotron. While the image is being created, the cleaning system is not active, and when the toner begins to transfer to the paper, it turns on. The first cleaning step is to recharge the residual toner powder, i.e. its potential changes from negative to positive. For this purpose, a cleaning roller is used, which is supplied with an alternating sinusoidal voltage with a positive constant component. This roller is pressed against the surface of the drum during cleaning, and is folded back during image creation. The roller is controlled by an eccentric cam, which in turn is driven by a solenoid (Fig. 16).

The positively charged toner is then transferred to the image drum, which still has a negative bias voltage. And already from the surface of the photodrum, the toner is cleaned with a cleaning squeegee of the photodrum cleaning unit (Fig. 17).

The creation of a full-color image ends by fixing the toner on paper using temperature and pressure. A sheet of paper passes between two rollers of the fixing block (oven), is heated to a temperature of about 200 ºС, the toner is melted and pressed into the surface of the paper. To prevent toner from sticking to the fuser, a negative bias voltage is applied to the heating roller, causing the negative toner powder to remain on the paper rather than on the Teflon roller.

We examined the operating principle of only one printer from one company. Other manufacturers may use other principles of image formation and other technical solutions when building printers, however, all these solutions will be very close to those discussed earlier.

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 a serial laser Xerox printer 9700, which printed at 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.

Drum charge

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.

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