LED printers use a set of light-emitting diodes (LEDs) to perform scanning photosensitive imaging. LED photosensitive imaging uses a dense LED array as a light emitter to convert the electrical signal of data information into a light signal and then Emitted onto the photosensitive drum for imaging. Laser printing imaging technology transmits all data signals to a transmitting device, and the emitted light is reflected by a rotating polygonal mirror and then imaged on the photosensitive drum. As a result, the imaging process of LED technology is obviously simpler than the laser imaging process. Because of this, LED printing technology is usually slightly faster than laser printing.
The toner cartridge of the LED printer plays an important role in the fixation imaging, which will directly affect the blackness of the printed product. Its core parts: toner, photosensitive drum, charging roller, magnetic roller and scraper play the following roles:
1. Toner is an attachment that is directly melted on the printing medium. The scientific proportion of the main ingredients plays a decisive role;
2. As the core component of exposure imaging, the photosensitive drum's photosensitive performance also plays a decisive role in the blackness of the printed product;
3. The charging roller (also known as the rubber roller) is used to prepare for exposure and imaging. The quality of charging the photosensitive drum will directly affect the degree of exposure and thus the blackness of the printed product;
4. As a direct participant in the entire primary transfer, the magnetic roller plays two roles: adsorbing toner particles and charging the toner particles;
5. There are scratches on the surface of the magnetic roller The area is non-sticky, so that the relevant areas corresponding to the printed product will also appear blank. In addition, when the magnetic roller has been printed for three cycles, an aging layer has appeared on its surface, which will also affect the charging effect of the magnetic roller on the toner, thereby directly affecting the amount of toner transferred from the magnetic roller to the surface of the photosensitive drum, that is, Directly affects the blackness of the printed matter;
6. The main function of the powder bin scraper is to control the number of toner particles on the surface of the magnetic roller, and its auxiliary function is to charge the toner particles, so it also directly affects the printed matter. of blackness.
The developing magnetic roller is an important component for carrying toner. The permanent magnetic core does not rotate. Its function is to use magnetism to absorb toner to the surface of the magnetic roller. The surface of the magnetic roller is sprayed with a rough graphite layer, which forms electrical holes with the toner scraper to facilitate toner transfer. When the magnetic roller carrying toner rotates out of the scraper position, the toner on the surface of the magnetic roller is not only charged, but also forms magnetic spikes, that is, toner mist, due to the force of the magnetic field, exerting a bias on the outer sleeve of the magnetic roller. Press so that the magnetic spikes are arranged in an orderly manner. The function of the magnetic roller spacer is to control the effective attraction distance between the magnetic fringe on the surface of the magnetic roller and the photosensitive drum, which is beneficial to improving toner runout and imaging.
The photoconductor material on the surface of the photosensitive drum is an insulator in the absence of light and is in a neutral state without any charge. To achieve an electrostatic latent image on the surface of a photoconductor, the surface of the photoconductor must be charged. Only in this way, when the laser beam scans onto the photoconductor, the photoconductor is conducted at the exposed points to form a beam lattice. The lattice charge conducts with the substrate to form a potential difference latent image. When the photosensitive drum rotates to a position tangent to the developing magnetic roller, the magnetic roller carries toner with opposite charge properties to the surface of the photoconductor and is attracted to the surface of the photosensitive drum. The toner image appears on the photoreceptor drum.
The electrostatic latent image formed on the surface of the photoconductor is developed to display the toner image. This process is called electronic development. The development work is completed by the developer, whose function is to turn the electrostatic latent image into a visible image. Development is accomplished by utilizing the principle that like charges repel each other and opposite charges attract each other.
The developer is filled with iron powder and carbon powder. After friction, the iron powder becomes positively charged and the toner powder becomes negatively charged. In this way, the iron powder is surrounded by carbon powder and the iron powder that has adsorbed the carbon powder is permanently The magnet attracts and forms a brush-like layer of iron powder and carbon powder mixture. When the toner drum surface passes under this layer of magnetic brushes, the toner is negatively charged and is attracted to the part of the toner drum surface that still maintains a positive charge, forming a visible toner image. The function of the stirrer is to make the iron powder and carbon powder frictionally charged.
The electrostatic latent image charge on the surface of the photosensitive drum is of opposite polarity to the charge carried by the developing toner. When the photosensitive drum and the magnetic roller carrying the toner come close to a certain distance, the toner is attracted. In other words, the toner jumps to the surface of the photosensitive drum to form a toner image, which is also called bounce development. Note: The charge of the electrostatic latent image on the surface of the laser-printed photosensitive drum after exposure is negative polarity, while the charge carried by the toner is positive polarity. Toner transfer to the developing unit is accomplished in this way.
When the toner is evenly stirred by the stirrer in the toner box, the toner is carried by the doped carrier and is adsorbed to the outer surface of the magnetic roller by the permanent magnetic core in the magnetic roller. Does not show polarity. When the magnetic roller carries the toner and rotates tangent to the toner scraper and rubs against it, the toner becomes positively charged. Under the action of the toner scraper and the magnetic field, the toner forms a very thin and evenly distributed toner mist on the surface of the magnetic roller. The toner scraper also plays a role in limiting the amount of toner so that it does not absorb too much.
As can be seen from the above, the magnetic roller plays an important role in the LED printer, and the quality of the magnetic roller directly affects the quality of printing. Domestic magnetic rollers have rough surface workmanship, poor smoothness, poor consistency of magnetic performance indicators, and unstable quality. During printing, due to the inconsistent magnetic properties of the magnetic roller, serious "printing" occurs and the uniformity of the totem is poor.