Electrophotography – Image formation – Development
Reexamination Certificate
2002-05-28
2003-12-30
Grainger, Quana M. (Department: 2852)
Electrophotography
Image formation
Development
C399S231000
Reexamination Certificate
active
06671479
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to systems and methods for generating monochrome and/or highlight color images at high speed.
2. Description of Related Art
In electrophotographic printing, a photoconductive surface is charged, and is then selectively exposed to image data to selectively discharge portions of the charged photoconductive surface. This forms a latent electrostatic image on the photoconductive surface. Charged toner material is then applied to the latent-image-bearing portion of the photoconductive surface to convert the latent electrostatic image into a developed image.
In full color image-on-image systems, this process is repeated a number of times to build a multi-layer full color image. This developed, or toner, image is then transferred, either directly, or indirectly via a transfer member, to a sheet of recording material. The developed, or toner, image is then at least semi-permanently fixed to the sheet of recording material. An example of this process is more fully described in U.S. Pat. No. 2,297,691.
In the image-on-image technique, a first latent toner image is developed onto a portion of the photoconductive surface. Subsequent latent toner images are exposed through the first image, on the same portion of the photoconductive surface, and then developed.
Different color features of an input image are formed at separate stations of the image forming device. Each station typically contains a charging substation, an exposing substation and a developing substation. These stations and substations are arranged around, and can be strategically spaced relative to, the photoconductive surface. Thus, in such image forming devices, the photoconductive surface is often a photoconductive belt. The speed that the belt moves past these different stations can be strategically set to allow adequate time for: 1) uniform charging of the photoconductive surface, 2) sufficient exposing of the latent image and 3) sufficient developing of the image.
Commercial demands require the reliable, high-speed production of quality images. Most full color image forming devices are capable of printing about 40-80 pages per minute. More sophisticated full color image forming devices can print up to 100 pages per minute.
SUMMARY OF THE INVENTION
Current full color xerographic image forming devices are able to form monochrome and highlight color images, but only at the lower full color rate, as the operating speed of such image forming devices is optimized for full color printing. Additionally, each station is dedicated to creating and developing a single color of toner.
However, the inventors have recognized that, when printing monochrome or highlight color images, various charging, exposing and/or developing substations of different color stations that are not being used, because the image does not contain that color toner, could be used in tandem with other charging, exposing and/or developing substations from other stations, to allow an increase in the process speed. Moreover, those stations and/or substations that are not being used can be physically absent or functionally-omitted in the monochrome and/or highlight color image forming device. For example, a full color xerographic image forming device can be converted to a dedicated monochrome or highlight color image forming device by physically or functionally removing some substations of the now-unused color toner stations. The remaining substations of the currently-unused color toner stations can now be used in tandem with some of the substations of the in-use color stations to allow an increase in the process speed.
This invention relates to selectively depopulating and/or repopulating a full color image forming device.
This invention also relates to using a multiplicity of charging substations in tandem to uniformly charge the photoconductive surface.
This invention also relates to using a multiplicity of developing substations in tandem to develop a single latent image.
This invention provides an image forming device having a set of image forming substations that have been selectively depopulated and/or repopulated relative to a full color image forming device.
This invention also relates to using multiple, functionally-equivalent, substations in tandem to perform charging, exposing, and/or developing actions on a photoconductive surface of a selectively depopulated and/or repopulated full color image forming device.
This invention separately provides systems and methods for selectively depopulating a full color image forming device and for generating the depopulated image forming device according to a set of operating parameters that allow higher speed printing of monochrome and/or highlight color images.
This invention separately provides a depopulated and/or repopulated image forming device that includes:
In various exemplary embodiments of the systems and methods according to this invention, substations, or even entire stations, of a full color image forming device can be removed from that full color image forming device to generate monochrome and/or highlight color images at a higher printing speed. As a result, the photoconductive surface does not spend time at stations and/or substations that are not needed to produce the monochrome and/or highlight color images of interest.
In various exemplary embodiments, a depopulated and/or repopulated image forming device is formed by physically omitting stations and/or substations relative to the stations and substations that are included on a full color image forming device. Additionally, stations and/or substations that are not normally included, or arranged differently, in the full color image forming device can be included to form a repopulated image forming device.
In various other exemplary embodiments, a depopulated and/or repopulated image forming device is functionally obtained from a full color image forming device by using an operation control scheme that functionally omits some of the stations and/or substations that are physically present in the full color image forming device and usually functionally active when forming full color images. Additionally, stations and/or substations that are physically present in the full color image forming device, but that are not necessarily functionally active when forming full color images, can become active under this operations control scheme to repopulate the depopulated image forming device.
In various other exemplary embodiments of the systems and methods according to this invention, multiple, functionally-equivalent, substations from different stations of a selectively depopulated and/or repopulated full color print engine can act in tandem to perform their function on a single portion of the photoconductive surface. As a result, the photoconductive surface can spend less time at a particular substation and still generate a monochrome or highlight color image having sufficient image quality, by making up for charging, exposing and/or developing deficiencies occurring in one substation with one or more other substations along the photoconductive belt. In this way, a single portion of the photoconductive surface may be charged, exposed and/or developed, multiple times in tandem, using different substations.
In addition to selectively depopulate and/or repopulate the print stations that are arranged along the circumference of the photoconductive surface, various exemplary embodiments of the systems and methods according to this invention use image-next-to-image printing. With image-next-to-image printing, different toner images are exposed onto different portions of the photoconductive surface. As a result, image generation can occur at a fast rate, because there is no need to expose through previously-developed toner images.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.
REFERENCES:
patent: 2297691 (1942-10-0
Grenek Heidi M.
Sharma Naveen G.
Wilcox David G.
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