Color laser printers are typically designed and operated with four separate color toner cartridges, one each for the colors cyan, magenta, yellow, and black. Conventionally, the toner cartridges are installed into, or removed from, a printer one at a time. Additionally, each individual toner cartridge is typically a single use item that is disposed of when the toner is depleted.
When installed in a printer, the color toner cartridges are engaged in a toner cartridge carousel that rotates to deploy a specific toner cartridge within the printer as needed during a print job. Examples of such color printers having a toner cartridge carousel system include the Color LaserJet 8550 Printer manufactured by Hewlett Packard, and the Color Laser Printer, Phaser 780, manufactured by Tektronix (color printers by Xerox).
A laser printer has a microprocessor that controls a laser light beam, and directs the laser beam to electrically charge a surface material on the surface of a toner transfer drum. Each surface area of the drum that is electrically charged by the laser beam is a single dot that will facilitate printing toner on a print medium. The areas of the drum that are not electrically charged by the laser beam will not print toner on the print medium.
The printer rotates the toner cartridge carousel to position one of the four color toner cartridges next to the drum. As the drum rotates and passes next to the toner cartridge, the electrical charge on the surface of the drum attracts the toner which has an opposite static charge from that of the charge on the drum. The toner adheres to the drum in a pattern of small dots wherever the laser beam created an electrical charge on the surface of the drum.
The printer also passes a static electrical charge to a print medium as the medium passes through the printer. Typically the electrical charge applied to the print medium is the same (positive or negative) as the electrical charge on the surface of the toner transfer drum, except that the electrical charge on the print medium is stronger. The drum with the adhered toner turns and presses against the print medium as the medium is passed through the printer. The stronger electrical charge of the print medium pulls the toner off of the drum and onto the print medium. The print medium then passes through a fusing system where pressure and heat permanently bind the toner to produce a printed page.
FIG. 1 shows a color laser printer 10 with a conventional toner cartridge carousel configuration 20. The carousel configuration 20 includes four separate toner cartridges 22 (two toner cartridges are not shown), a carousel central component 24, and a toner cartridge engaging mechanism 26 to secure the toner cartridges 22 within the printer 10. The carousel central component 24 is integrated and mechanized with the color printer 10 and is not removable from the printer in the ordinary course of printer operation (e.g., removing and installing toner cartridges).
The carousel configuration 20 rotates the toner cartridges 22 as needed by the printer 10 during a print job. As illustrated in FIG. 1, only two of the four separate and individual toner cartridges 22(a) and 22(b) are visible from outside the printer, and only one toner cartridge 22(a) can be removed or inserted at any one time. Two of the toner cartridges 22 are inaccessible and not visible due to their location on the carousel 20 which rotates the cartridges behind the framework of the printer 10 during operation.
There remains the ever-present need to reduce the expenses incurred during the manufacture and operation of printing devices. In light of conventional color printing devices having four separate toner cartridges that require an independent carousel mechanism for operation, manufacturing expenses can be reduced with an improved toner cartridge assembly. Furthermore, in light of the toner cartridges being single use, disposable items, operating expenses can be reduced with an improved toner cartridge.