Laser printer has high voltage circuit and high temperature circuit, so the electronic radiation and thermal radiation have certain impact on human body. We should pay attention to the protection of pregnant women and children or keep away from these devices. In the process of printing, high temperature heating will bring out some powder and ink particles, which is not good for breathing. We should try to avoid working at the edge of laser printer for a long time.
The photoconductive material on the surface of the drum is an insulator in the absence of light, in a neutral state, without any charge. In order to realize the "electrostatic potential image" on the surface of photoconductor, the surface of photoconductor must be charged. Only in this way, when the laser beam is scanned on the photoconductor, the exposed point of the photoconductor is conductive to form a beam lattice. When the drum rotates to the tangent position with the developing magnetic roller, the toner on the magnetic roller which has the opposite charge property with the photoconductor surface is attracted to the drum surface, so that the toner image appears on the drum.
In order to make the drum absorb the toner according to the image and text information, the drum should be charged first. The charging electrode is a tungsten wire parallel to the drum axis, which has 5-7kv DC high voltage. When the drum surface is very close to the tungsten wire, the surrounding air is ionized to produce corona discharge, which makes the drum charged. The positive and negative voltage is determined by the voltage of tungsten wire. If the photoconductive material is selenium tellurium alloy, it will be charged positively. After the drum rotates for one cycle, the whole surface will be charged.
For laser printer manufacturers, most of the laser printers produced in modern times are charged by charging roller. Due to the contact charging mode, it does not need high charging voltage and no ozone is generated. However, due to the accumulation of ionized dust, the abrasion of the drum is increased and the charging is uneven.