How does the printer work?
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Depending on the method of creating images, all printers are divided into matrix, inkjet, laser and 3D printers. The most common in our time are inkjet and laser printers. About how they work, we will tell in more detail.
How inkjet printers work
The image in an inkjet printer is formed from individual microscopic points of a particular color. Each point is obtained from one tiny droplet of liquid ink, which is injected onto the paper through nozzles — very small holes whose diameter does not exceed several tens of microns. The quality of the resulting image directly depends on the diameter of the nozzles - the smaller the diameter, the higher the quality.
The main components of an inkjet printer and the mechanism of their work
- The printhead is the main node of any inkjet printer. It is in it there are nozzles, to which ink is supplied. Tanks with ink, the so-called cartridges, can be built directly into the printhead, in other models they are installed separately.From the cartridge, the ink is fed through the capillaries into a miniature storage chamber located above the nozzle, but they cannot pour out through the nozzle themselves - they are held by the force of the surface tension of the liquid. Therefore, a drop must be pushed through a microscopic hole. For this, there is a special mechanism in the head that implements this process. Droplet ejection in inkjet printers can be done in one of two ways — piezoelectric orthermal.
- In the piezoelectric printhead, a piezoelectric element is located above the nozzle, which is bent under the action of an electric current pulse and thus creates an elevated pressure area. As a result, a drop of ink is pressed through the nozzle.
- In the thermal inkjet print head, a miniature heating element is mounted in the ink chamber. When a current pulse passes through it, the element instantly heats up to several hundred degrees, the ink from this literally “boils”, tiny gas bubbles are formed in them, which push a drop from the nozzle.
- Piezoelectric heads are more reliable and cheaper than thermal jets.In addition, with the same diameter nozzles, piezoelectric heads create a better image.
- The carriage moves along a special guide across the paper sheet. On it the printing head is fixed. The carriage performs reciprocating movements during which drops of paint are injected in the correct order from the print head to the paper.
- The transport mechanism with rubberized rollers captures a sheet of paper from the tray, feeds it to the place of printing and pulls the sheet under the moving carriage.
- Optical and mechanical sensors control the entire printing process, starting from loading the sheet and ending with obtaining the finished image.
- Control system. Synchronous operation of all nodes of the printer and its communication with the computer provides a built-in microprocessor. The buttons and lights on the control panel allow you to control the operation of the printer and visually monitor the printing process.
How does a laser printer work
In a laser printer, the process of creating an image is based on a completely different principle - the principle of xerography.
- First, electronic information about the printed image is sent to the internal memory of the laser printer. There it is processed and after that the built-in microprocessor begins to send commands to the laser beam, which, passing through a system of focusing lenses and mirrors, begins to draw an image line by line on the photosensitive rotating drum.
- A drum is a metal cylinder coated with zinc oxide, which is a light-conducting semiconductor. On the entire surface of the drum, a negative static charge is generated by the charging roller. A laser-controlled laser beam in the right places illuminates points on the surface of the drum where the charge is removed under the influence of light. Thus, on the photosensitive drum, a copy of the image is drawn, drawn by electrically charged and uncharged dots.
- Next, the drum is in contact with another roller in the process of rotating the toner feed. Toner is the smallest coloring powder, the particles of which are attracted to the charged points on the photosensitive drum and stick to them, while acquiring a negative charge.
- A clean sheet of paper is picked up by rubber rollers from the feed tray, fed to the print location. The photodrum at this time rotates, rolls on the sheet, which from the inside out presses one more roller to it. This video not only presses the paper, but also creates a positive charge on it. Negatively charged particles of toner are attracted to the positively charged surface of the paper sheet and “jump over” it from the photosensitive drum. So on paper the image turns out. But it is not quite ready yet, since the toner is kept on the sheet only due to the forces of electromagnetic attraction.
- In order to fix the toner on paper, it must be baked. The sheet with the image is sent to the "stove", where it is rolled between two shafts - rubber and aluminum. The rubber roll presses the sheet, and the aluminum, heated to 200 * C, melts the toner into the paper.