A toner cartridge is used in an image forming system, such as a copying machine, a facsimile or a printer, for supplying a toner for forming an image. The toner is generally comprised of a cylindrical container and a cap. The toner container has an opening in it that allows the toner to be discharged into the toner hopper. The cap is adapted for closing the opening portion. When in use, the cap is removed from the container, and then the container is loaded in the image forming system. After toner used up, the container must be removed from the image forming system for a replacement. A toner comprises a binder resin, a colorant and other additives. Most of the toners are generally composed of magnetic oxides of iron with a small amount of carbon black for die, all encapsulated or mixed in styrene. The styrene is the major component, making up over fifty percent of the toner in many formulations used in the market. Processes for preparing the toner include a kneading pulverizing method, in which a colorant, a charge control agent, a parting agent and the like are melted and mixed into a thermoplastic resin, which becomes a binder resin component, and dispersed evenly to form a composition, which is then pulverized and classified to obtain colored particles. Modern toner cartridges often include a variety of sensors that interact with the laser printer to indicate the status of the cartridge. Indications relating to toner level, print quality and general cartridge function are often included as well. The sensing system typically includes an encoder wheel interconnected with a rotating beater blade within a cylindrical toner tank. Movement of the beater blade feeds toner into the metering system. The encoder wheel reports the movement of the beater wheel through the rear housing. Toner cartridges manufactured by original equipment manufacturers typically have components including the wiper blade and/or doctor blade, depending upon the type of process employed. In addition to the wiper blade, toner cartridges typically also include a doctor blade. The doctor blade serves to meter a uniformly thin layer of toner particles on the surface of a rotating developer roller that has acquired a deposit of toner on its surface, and functions to help uniformly charge the toner deposited on the surface of the developer roller. After passing the doctor blade, a portion of the toner on the developer roller is in turn transferred to the surface of the photoconductive drum carrying the latent image to be printed.

The developing unit of the image forming apparatus comprises a developing roller and a developer storage chamber having a stirring and mixing unit. A developer used in an image forming method such as electrophotography, electrostatic recording or electrostatic printing is deposited onto a latent image bearing member, typically a photoconductor. The developer is transferred from the photoconductor to a transfer medium such as a transfer paper and fixed on a surface. In printing, a charging unit charges the surface of the photoconductive drum uniformly. An exposing unit illuminates the charged surface of the photoconductive drum in accordance with print data to form an electrostatic latent image. The developing unit supplies toner to the electrostatic latent image to develop the latent image into a toner image. The toner image is transferred onto print paper by a transferring unit. Then, the print paper advances to a fixing unit where the toner image is fused into a permanent image. Color images are typically formed by overlaying three primary color toner images and a black toner image. Generally, four developing unites containing toners for cyan, magenta, yellow, and black colors are needed for a color electrostatic latent printer. The toner image is transferred directly onto a recording medium, or via an intermediate medium, from the photoreceptor. While the recording medium passes through a fusing unit, the toner image is fused onto the recording medium by heat and pressure. In order to prevent scattering of toner within an image formation apparatus, the interior of the developing device and the outside are isolated one from another by a casing, except for an opening whereby a portion of the surface of a developing agent carrying member is made to face a latent image carrying member. During printing process, a small amount of toner is not transferred to the printing paper, but remains on the photosensitive drum. A developing unit generally has a cleaning means for cleaning waste toner remaining on the photosensitive drum. Toner that remains on the photoconductive drum after transfer is removed from the photoconductive drum and collected into a waste toner tank provided in the print process cartridge. This used or waste toner must be removed before the drum revolves around to pick up the toner for the next page or unwanted printing can occur. This task is often accomplished with a cleaning blade which wipes any remaining toner off of the drum.

Known developers include a two-component developer composed of a toner and a carrier, and a one-component developer composed of a magnetic toner or a non-magnetic toner alone. When a two-component developer is used, the developer which is prepared by mixing toner with a carrier (magnetic powder) under agitation in the developer storage chamber and is charged is contacted to the developing roller to form a developing brush which is contacted to a latent image formed on the photosensitive body to develop the latent image in order to form a toner image. The one-component developer can be classified into a magnetic toner and a non-magnetic toner. The magnetic toner includes a magnetic material such as magnetite and is held on a developer carrier such as a developing sleeve having a magnet provided therein. The magnetic toner forms a layer on the sleeve with the thickness thereof being adjusted by a suitably thickness control member such as a blade or a roller. The non-magnetic toner of the one-component developer is supported on a developing sleeve by electrostatic force. The non-magnetic toner is supplied to the substrate by being pressed with a supply roller to form a layer thereon. The thickness of the toner layer is adjusted by a suitable thickness control member such as a blade or a roller. This one-component development system is known as an advantageous development system because it can provide an image with a high image quality and high resolution. The two-component developer has a problem because the toner particles gradually adhere on the surface of the carrier. The concentration of the toner in the developer gradually decreases as only the toner is consumed. The one-component developer is free from the above problems and, therefore, the size of the apparatus can be compact.

Laser printers use a focused light beam to expose discrete portions of an image transfer drum so that these portions attract printing toner. A regular process cartridge for a laser printer is generally comprised of an electrophotographic photosensitive member, developing means, charging means, cleaning means, and a toner container. A dry type color laser printer forms an electrostatic latent image on a photosensitive substance, develops the image using powder toner, and transfers the developed image on a sheet of paper through a predetermined transferring medium to form the image on the paper. In color laser printers, a one-drum type is becoming main stream. The one drum type image forming apparatus is classified into two categories. One of them is an intermediate transfer system, in which a plurality of color toner images are formed on an image bearing member and primarily transferred and superimposed onto an intermediate transfer member. The superimposed color toner images are then secondarily transferred onto a transfer medium. Another type is a direct transfer system, in which a transfer medium is carried and conveyed by a transfer drum and a conveyance belt. A plurality of color toner images are formed on image bearing members and are transferred onto a transfer medium in turn, and thereby a full color toner image is formed. In such laser prinres, a plurality of developing devices are commonly used and accessibly arranged in the vicinity of an image-bearing member, so that respective color toner images are formed per its rotation and transferred from the image-bearing member to the transfer medium to form a full color toner image thereon. Toner cartridges for laser printing are engineered and manufactured to a high degree of precision necessary for proper operation and good printed image quality.

Toner cartridges are manufactured in many different configurations and sizes. The differences between printer cartridges for various types of printing devices may only be slight or subtle. In many cases, a manufacturer will produce cartridges that are substantially similar in overall configuration to each other. A toner is often called a consumable because it must be replaced after depletion. The components included in a toner cartridge such as a toner container, seal assembly, mounting member, development roller assembly, photoconductive drum assembly and charging corona or roller assembly, are also commonly identified as consumables because they too have a limited life. Since used toner cartridge has many components that may be recycled. An industry known as the remanufacturing industry has arisen to take advantage of this fact. Remanufacturers take used toner cartridges, clean them, repair damaged components, replace worn out components, add new toner, and reintroduce these refurbished cartridges into the marketplace.