How does a Toner Cartridge work?



A toner cartridge is used in the laser printer process. The toner cartridge has a rigid plastic housing that is replaceable, recyclable, and reusable. It contains following parts that are replaced in order to recycle the cartridge.

  • Toner Powder
  • OPC Drum:
  • Wiper Blade
  • Doctor Blade
  • Magnetic Roller
  • PCR (Primary Charge Roller)
  • Chip
  • Developer
  • Recovery Blade

So in order to clarify how it works the following is a brief explanation of the laser printing process.

  • First, you insert the paper into the laser printer and send the printing command from the computers, at that moment the OPC drum surface is charged positively while the drum rotates.
  • Second, a laser beam sends a light onto the OPC drum surface during the rotation, and then the area exposed to the laser beam forms an electrostatic image to be printed.
  • Third, the toner particles are charged and then attracted to the electrostatic image on the drum.
  • Fourth, while this is happening the paper is passing through the drum where it receives negative charges causing the toner to stick to it from the drum surface to the paper.
  • Fifth, once the image is transferred to the paper by the static electricity it is fixed into it by heat and pressure given by the heat roller and the pressure roller within the fuser assembly.

As you can see it is simpler than it looks! So start printing…

  • Toner Powder is the ink in powder form, used by laser printers and photocopy machines.
  • The OPC Drum is an aluminium cylinder coated with a layer of non-toxic, organic-photoconductive (OPC) material which becomes electrically conductive when exposed to light. Most drums will rotate 3 times to cover a single letter size page. This means that only 1/3 of the image can be placed on the drum at one time.
    During the printing process, a high voltage is applied across the PCR and it rotates against the drum thereby coating the light sensitive surface of the drum with a negative electrostatic charge. A laser beam traverses the surface of the OPC drum and selectively discharges negative charge from the parts of the surface of the drum. It thereby composes an invisible electrostatic image on the drum. This invisible electrostatic image turns into a visible image when negatively charged toner particles are deposited on the exposed areas of the drum. Hence the quality of the surface of the OPC drum is a significant determinant of print quality. The OPC drum is typically designed to last about 1.5 times the rated life of the cartridge and hence the cartridge cannot be re-used for a complete cycle unless the drum is replaced. It is conceivable that original manufacturers use such OPC drums to discourage the re-filling or re-manufacturing of their toner cartridges.
  • The Wiper Blade is a cleaning blade which sits in contact with OPC drum. As the drum rotates during printing, excess toner is removed from the drum surface and stored in the waste toner receptacle inside the toner cartridge.
    The wiper blade is a polyurethane strip that rides against the length of the drum and covers the waste bin. As the drum rotates with the 1/3 of a page image on it, and places the image on the paper, some of the toner is still left on the drum and must be cleaned off before the next 1/3 of the image can be placed on the drum. If it is not cleaned off, the first 1/3 of the image will be repeated in a ghost-like background of the second 1/3 of the image, and the second 1/3 of the image will also be repeated in a ghost-like background of the third 1/3 of the image. The wiper blade prevents this from happening. However, the edge of the wiper blade must be precision sharp and smooth. The slightest little nick, scratch, or bow will allow unwanted image to pass through and may result in a ghosted repeated image, scratch marks, or lines on the page. As the wiper blade scrapes the toner from the drum, it drops it into the waste bin. Because the toner in the waste bin has been charged, it can no longer be used.
  • Doctor Blade controls the flow of toner transferred from mag roller on to the OPC drum.
  • Magnetic Roller consists of a metallic cylinder that rotates around a fixed magnetic core. It is usually referred to as the magnetic roller or "mag" roller. Mag Roller assists the transfer of toner from the reservoir onto selected areas of the OPC drum. These parts also wear and need to be inspected and replaced if necessary.
  • PCR (Primary Charge Roller) is a solid rubber roller with a metal core. It is located beside the OPC drum. During the printing process, a high voltage is applied across the PCR and it rotates against the drum thereby coating the light sensitive surface with a negative electrostatic charge. With usage, the surface of the rubber roller can wear or be damaged by contaminants, necessitating its replacement. Any damage to the PCR can result in subsequent damage to the surface of the OPC drum since the two surfaces rotate in contact with each other.
  • Chip: Most manufacturers have installed chips on their cartridges to confirm that a correctly matched, new cartridge has been installed in the printer and for tracking of the life of the cartridge. Most of these chips reset a page count when they are first inserted into a printer: the counter runs backward to zero and the printer will then demand the insertion of a replacement cartridge.
  • Developer roller which assists the transfer of toner from the reservoir onto selected areas of the OPC drum.