Color imaging devices are becoming increasingly popular as the desire for color imaging capabilities continues to increase. Modem color printers can use a number of different technologies to produce output on print media. A color ink-jet printer uses small droplets of a few base colors, and dithers them in a pattern to produce varying colors. A color laser printer places small dots of toner, also from a few base colors, and dithers them to produce the varying colors. Color image forming systems for color image forming apparatuses are roughly classified into four types of transfer drum system, intermediate transfer system, image-on-image system and tandem system. In the intermediate transfer system, a full color image is formed by transferring toner images of colors in sequence onto a drum or a belt called an intermediate transfer member in place of the transfer sheet used in the transfer drum system, and then, the full color image is transferred again onto a transfer sheet by one operation. The image-on-image system is a system in which an image is transferred onto a transfer sheet by repeating an electrophotographic process consisting of formation, development and transferring of an electrostatic latent image with respect to each of yellow (Y), magenta (M), cyan (C) and black directly on a photosensitive member. In the the transfer drum system, a transfer sheet wound around a transfer drum composed of a dielectric film is disposed opposite to a photosensitive member, and toners of yellow (Y), magenta (M), cyan (C) and black (Bk) are superimposed on the transfer sheet in sequence by repeating an electrophotographic process consisting of formation, development and transferring of an electrostatic latent image with respect to each of the colors, thereby obtaining a full color image. The tandem system is a system in which a full color image is obtained on a transfer sheet by transferring images formed by image forming units in sequence onto a single piece of transfer sheet fed by a transfer belt. Among them, the color image forming apparatus of the tandem system has excellent characteristics. Because it can use a large variety of transfer sheets, obtain a full color image of a high quality, and obtain a full color image at a high speed. Color laser printers implement an electrophotographic process for recording and registering a multi-color image on an electrophotographic surface or a print medium, such as paper. Image data representing each primary color plane and generated in a personal computer are sent to the laser printer, which converts the image data to binary electrical signals that represent the dots forming the image. Each of the binary signals represents either a light or dark state of one dot in the image pattern. In the field of laser printers capable of forming color images, there has recently been an increasing popularity in tandem-style color laser printers. These laser printers are provided with a photosensitive drum for each color and a charging device, scanning device, and developing device disposed around the photosensitive drum. In tandem color laser printer, a toner image in each color borne on the respective photosensitive drum is transferred onto a sheet of paper one after another, enabling the rapid formation of color images.

The principles and operations of a color laser printer are similar to those of the black-and-white laser printer. The only difference is that the color laser printer has to execute four times the operations of: charge disposition, emitting laser beams onto the image roller and forming an electrostatic image, attracting toner contained in each of the toner cartridges with the electrostatic image, transferring the image, and discharging charges and feeding the printing media through the fuser to melt and adhere the toner. A color laser printer develops successive images by using developing toners of different colors supplied from corresponding toner sources. A typical color laser printer uses the four-cycle printing method, wherein a multicolor image is formed on an image-support member by four rotations of a photoconductor such that a monochromatic toner image is formed at each rotation of the photoconductor, and then the multicolor image on the image support member is transferred to a recording medium. Color printing is typically done with the substractive primary colors cyan, magenta, and yellow and with black. All of these colors are applied in registration during successive rotations of the drum before transfer of the toner to the print medium. Heat is usually applied to permanently fuse the image to the print medium to form a finished multi-color image. The four-cycle type color laser printer including four developing rollers provided according to the colors of cyan, magenta, yellow and black, a photosensitive body for forming electrostatic latent images developed by the developing rollers, an intermediate transfer body disposed opposite to the photosensitive body, and a transfer roller disposed opposite to the intermediate transfer body. In the four-cycle type color laser printer, electrostatic latent images formed successively on the photosensitive body are developed successively by mono-color toners provided from the developing rollers provided according to the colors. Mono-color toner images are formed successively on the photosensitive body. The mono-color toner images are transferred successively onto the intermediate transfer body so as to be superposed on one another. The multi-color toner image is transferred onto a sheet of paper by the transfer roller. Thus, a multi-color image is formed on the sheet of paper. Color printing by an inline laser printer is achieved by scanning a digitized image onto a photoconductor using lasers. Such a printing process is known as electrophotographic printing. In an inline color electrophotographic imaging process, latent images are formed on a plurality of photosensitive drums, which are in turn developed using a predetermined color of toner. The developed images are transferred to an intermediate transfer device or directly to a sheet of media, such as paper, which travels past the photosensitive drums. Each color image is created one line at a time and the lines are oriented at right angles to the direction of travel of the intermediate transfer device or the paper. The individually generated images on each drum are combined on the paper to form a single full-color image. The lasers generate beams of laser energy which are pulsed according to the digitized data to be imaged on the photoconductor. The typical inline color laser printer utilizes a plurality laser scanners to generate a latent electrostatic image for each color plane to be printed. The four color planes typically printed, and which are generally considered as necessary to generate a relatively complete palate of colors. These colors will be known herein as the base colors.

A laser printer generally comprises a printer body, a developing device disposed in an inside of the printer body with a photoconductive drum, a laser scanning unit projecting a laser beam to the photoconductive drum to form an electrostatic latent image thereon, and a toner supply unit supplying toner to develop the electrostatic latent image formed on the photoconductive drum. A color laser printer for forming a color image includes a plurality of developing devices, a photosensitive belt, an intermediate transfer body, and a fixing unit. Each developing device stores a different color of toner and includes a developing roller. The photosensitive belt bears a visible image developed by the color of toner supplied from the corresponding developing roller. The quality of the image printed on the paper depends upon the quality of the latent electrostatic image formed on the photoreceptor belt by the laser scanner. The color laser printer further includes an exposure unit. The exposure unit selectively exposes the photosensitive layer to laser light to form an electrostatic latent image on the photosensitive member. When the developing cartridges are mounted in the casing of the color laser printer, the developing roller of each developing cartridge is disposed in confrontation with photosensitive member so that the toner borne on the surface of the developing roller develops the electrostatic latent image into a visible toner image. Some multi-color printers employ a print engine to which print data is supplied in a "race" mode. In such printers, the print engine operates at a constant speed and rasterized image data is made available at a rate which keeps up with the engine's operation. Image data for a color laser printers is digital data which is stored in computer memory. The data is stored in a matrix or raster which identifies the location and color of each pixel which comprises the overall image. The raster image data can be obtained by scanning an original analog document and digitizing the image into raster date, or by reading an already digitized image file. Most color laser printers today receive an image of a page to be printed in the form of a page description language and construct a page description which is then fed to the print engine for rendering onto a media sheet.