Toner is a reasonably familiar substance to most people working in offices or for companies that have office photocopy machines and big industrial printers. These machines inevitably use toner to form images and text onto a sheet of media, usually being a plain white piece of paper. In other words the toner acts with the same purpose ink has, although ink is an aqueous solution whereas toner is in the form of powdery, dust-like solids. And due to the fact toner is a powder, cartridges should not be shaken as the material can spread through the air and adhere to unwanted surfaces, permanently dying them. Before handling any toner cartridge, make sure you are aware of the potential dangers and health risks involved with these units by clicking here.
In its early form, toner was a mix of carbon powder, iron oxide, and sugar. Eventually, to improve the quality of the printout, the carbon was melt-mixed with a polymer. The polymer is a thermoplastic that now comprises about 40 to 95 percent of the toner mixture and is crucial to binding and carrying colorant to the drum unit and substrate. The polymer is often referred to as the “binder” being able to hold the toner powder mixture together, carrying the powder to the transfer belt or drum unit, and holding the mixture in place for the heated fuser rollers to bind the powder to the paper with heat and pressure.
To better understand this process, let’s take a look at the different components that make up a toner cartridge and their functions. A basic toner cartridge contains several parts; one common component in each cartridge is the hopper which houses the toner powder until being picked up by a magnetic developer roller. The magnetic developer roller is a cylindrical sleeve used to transfer image forming toner powder particles to an image forming drum unit. This roller protrudes partially into the hopper and has several magnetic beads inside that will attract the toner powder mixture from the hopper to the roller during the printing process. As this piece rolls, the picked up toner is brushed against the drum unit.
The drum unit, having a greater static attraction, will once again pull the toner powder but this time from the magnetic developer roller. Any excess powder on the developer roller will be scrapped off with an MDR Doctor Blade before passing by the drum unit. The MDR Doctor Blade is a precision leveling blade that is designed to keep only one layer of toner powder on the developer roller. This ensures more evenly distributed toner and helps to prevent the drum and toner cartridge from clogging. The magnetic developer roller also has a secondary blade, known as the MDR Sealing Blade, to clean off any powder left on the surface of the roller after passing by the drum and before rotating back into the hopper section.
The drum unit itself is sometimes included with the toner cartridge in 2 in 1 or all inclusive toner cartridges. And whether the drum unit is a separate unit or has been included with the toner cartridge, the drum serves the same purpose. The drum is a photoconductive cylinder that contains a laser neutralized image of the project about to be printed out. A laser will actually neutralize parts of the drum unit, based off the desired image about to be printed. The neutralized parts of the drum will not be able to attract toner, which is how the drum forms an image, only being able to attract toner where desired on the image. Once the drum unit has picked up the toner powder from the developer rollers, the unit will then transfer them immediately to the paper substrate passing through the machine.
To keep the drum unit charged, a primary charge roller inside the toner cartridge rests against the unit, recharging the drum and eliminating neutralized areas of the unit. The drum also has a cleaning blade know as the Organic Photoconductor Wiper Blade. Any extra toner left on the surface of the drum unit after transferring the powder to the paper will be scrapped of by the wiper blade into the waste container. The last part to creating a printout involves the fuser rollers and some assisting transfer rollers that drive the media through the machine and are usually separately sold components that do not need to be exchanged as frequently as toner cartridges or even drum units.
All these components are necessary pieces to having a functional toner cartridge that can produce images onto a piece of paper using pigmented polymers, colorants, and carbons as the ink or image forming material being adhered to media. The current laser toner cartridge powders are comprised of a mixture of colorant pigments, external additives, and wax substances in addition to the binding polymers. The external additives can be iron oxide molecules, chemical release agents, charge control agents, and flow agents all designed to keep the mixture at optimal functioning compositions. Many toners now have protective wax coatings encapsulating each toner powder particle for longer lasting printouts and resistances to smudging and blurring.