A modern laser printer prints with dry ink using xerographic technology. Xerography is a copying technique that uses an electrical charge to transfer ink. A special ink for a laser printer is called toner and is sold in cartridges.
The work of a laser printer includes three stages: scanning, image transfer and image fixing.
Most often, printing is done on paper. It is placed in the paper feed box, after which the pickup roller pulls it into the printer, and the release pad assembly and separator separate the sheets so that they move inward one at a time.
What's inside the cartridge
1. Photocylinder - an aluminum shaft on which a photosensitive material is applied. The photocylinder is able to easily change conductivity under the influence of light. Its charge can persist for a long time, but if laser light falls on its surface, then in the illuminated places the conductivity of the photocoating will increase (due to a decrease in resistance), and a neutrally charged region is formed.
2. The primary charge shaft is a metal axle in a rubber sheath. It is designed to charge the photocylinder.
3. Magnetic roller - a hollow cylinder with a conductive coating on the outside and a permanent magnet on the inside, needed to transfer toner.
Image overlay process
With the help of the primary charge shaft, the photocylinder acquires an initial charge, it can be either positive or negative. After charging, the laser beam passes through a rotating drum, and the places it hits become neutrally charged. It is these overexposed areas that correspond to the image you want to print.
Then the magnetic roller comes into play, it feeds the toner from the cartridge to the photocylinder. Toner is attracted to the magnetic shaft (after all, there is a permanent magnet core inside it), and is electrostatically transferred to the drum. Since a neutral area is formed on its surface, the charged toner is attracted to it, and repelled from the charged areas.
The paper also receives a static charge that transfers toner from the photo cylinder to the paper. As soon as this happens, the neutralizer removes the charge from the paper so that it is not attracted to the drum itself.
Freeze the image
If you immediately remove the paper after drawing the pattern, the image can be easily destroyed with a movement of your finger. To prevent this from happening, the picture must be fixed. The composition of the toner contains substances with a certain melting point, under the influence of which the toner is literally fused into the paper, after which it solidifies.
The result is a sharp, durable image that is resistant to moisture and sunlight.
