The principle of operation of the laser printer

Laser printers are widely used for printing documentation in the office and at home. High print quality and speed due to design features. In order to understand the principle of operation of the equipment, it is necessary to study the device in detail. Briefly to consider this question does not work out, but the more detailed we analyze everything, the clearer the answer will be.

Laser printer device

The basis of the laser printer is the photoelectric principle of xerography. The design includes complex mechanisms and components that can be divided into three main blocks.

1. The basis is the printing mechanism.
2. The controller with raster processor is responsible for scanning.
3. Data exchange is carried out using the interface unit.

Elements of the printing mechanism:

• a photodrum with a static charge, changing depending on the lighting;
• the laser and the system of mirrors ensure the exposure of certain areas on the photodrum;
• intermediate block required to transfer the image to the final carrier;
• the unit of storage and supply of toner, which is based on the cartridge;
• mechanisms for pulling paper from tray to printhead;
• heating elements for the development of the image on the sheet.

How does the cartridge

Cartridge consists of toner and drum. The chemical composition of toner is crushed polymeric material. Powders, depending on the manufacturer, differ in consistency and physical properties. Toner is different from the ink quality of the image, but when working with him, be careful.

Important. For high-quality printing on a laser printer, you need to change consumables on time. Refilling cartridges with low-quality toner is not recommended.

The drum is a cylinder with a photoconductive surface. The magnetic shaft charges the toner, and the cleaning blade cleans up unused toner.

How does a laser printer work

The principle of operation of a laser printer is to create a preliminary image on the drum and then transfer it to paper. A high-quality print is obtained by pinpointing points on a photodrum using a laser and a system of mirrors. The principle of operation of a laser printer is based on the physical process of xerography.

To understand how the device prints, it is necessary to study in detail the steps and the principle of operation of a laser printer:

1. Image processing and drum charging with charged particles.
2. Next comes the preliminary creation of the image.
3. The next step involves developing with toner.

Fastening occurs with high temperatures. The design provides high quality printing and speed. Technology is constantly evolving, offering new solutions.

Photodrum charge

In order to form a preliminary image, it is necessary to create an electric charge on the surface of the drum. There may be positive and negative particles, depending on the printer model and design features.

There are two ways to transfer a charge:

• A coronator is a tungsten filament containing inclusions of gold or platinum. Under the influence of voltage, an electric field is created, which is transferred to the drum. With this method, the quality of the printed material deteriorates over time.
• The charge roller is a shaft coated with a layer of rubber or foam rubber. When interacting with the drum electricity is transmitted. With this method, a reduced voltage is formed, which allows extending the life of complex mechanisms.

Exposure

The process of creating a preliminary image on the drum is called exposure. On the surface of the drum is a semiconductor coating, which, when exposed to light, begins to conduct current. Illumination appears due to a thin laser beam and a complex system of mirrors.

For the given parameters, the beam forms an image, removing the charge on illuminated areas. Drawing a picture or text is dotted. The result is a surface of negatively charged particles. The rotation of the drum occurs with a stepper motor. Points are drawn around the entire circumference.

Developing

The image is manifested with toner and magnetic shaft. The mechanism is a metal tube with a magnetic core. With the help of rotation, the toner is attracted to the shaft. The dosing blade ensures uniform distribution of paint over the entire surface. The layer is formed by passing the toner through the gap between the blade and the drum.

Caution. It is necessary to properly install the mechanism to avoid the appearance of defects on the printed document. Excess toner leads to dots and stripes.

The magnetic shaft operates cyclically. In the process, new particles are attracted, creating an image. The excess powder is dumped into a special container.

Transfer

On paper, the image is also transferred using a charge. The moving mechanisms feed a sheet from the tray to the photodrum, next to which is the image transfer shaft. Toner particles are transferred according to a scheme on paper due to static voltage. Excess paint gets back into the bunker. With the help of special elements, dust and small particles are removed on the surface of the sheet. Recovery of charge after the whole cycle occurs with the help of a corotron. Then the process is repeated until the entire image is transferred to the paper.

Fastening

The next stage of printing on a laser printer is consolidated. This step is necessary for the image to remain on paper. Under the influence of high temperatures, the toner begins to melt, which allows you to firmly fix on the surface. When the sheet passes between the two rollers, heating occurs.

Reference. Depending on the model, the stove can heat the powder to 200-350 ° C.

Type of heating:

• Thermofilm is used in low-cost laser printers. It is highly susceptible to mechanical stress.
• Teflon design heats the surface with a lamp. Reliable and durable design.

The temperature is controlled by a sensor. In case of exceeding the values, the device automatically turns off. So that the sheet does not stick to the drum, there is a separating mechanism at the exit. In compliance with the basic rules of operation, these elements rarely fail.

Color print

Laser color printing is widely used to print high-quality images. Given that the printer creates a subtractive color model, it is possible to get any shade. This is due to the absorption and reflection of different light waves. With the introduction of black, the output is saturated colors. A laser printer consists of a large number of modules and blocks that allow you to mix colors, and transfer the image onto a sheet. Models differ in specifications and operating principles.

What printing principle is used in color laser printers?

Unlike a black and white printer, the principle of operation of color equipment is different. Before printing, the printer processes the image and breaks it into monochrome. A total of four primary colors are used: cyan, magenta, yellow, and black. For each of them has a separate compartment. In the process of printing shades are mixed. Models differ in design and principle of action.

Color printing methods:

1. In the first case, an image is formed for each individual color. Printing takes place in several passes, which affects the speed of processing the document. Due to the design features, such printers have large dimensions.
2. Modern models allow you to simultaneously apply on the drum all four primary colors. The image is transferred to the sheet in one pass. As a result of a sequential run, printing time is reduced, not at the expense of image quality. This method allows to achieve a more even color reproduction.

Color laser printer is a high-tech device. The product, as a rule, has its own processor and HDD. The technology of transferring the image to the intermediate section is widely used. The method allows to extend the life of the product, because there is no contact of the printing mechanism with the paper. Such devices are suitable for use in the office and at home.