Electrophotography – Control of electrophotography process – Color balance
Reexamination Certificate
2000-11-01
2001-11-27
Brase, Sandra (Department: 2852)
Electrophotography
Control of electrophotography process
Color balance
C358S001900
Reexamination Certificate
active
06324356
ABSTRACT:
FIELD OF THE INVENTION
The current invention is generally related to toner saving in image reproduction devices such as printers, copiers, facsimile machines and any combinations thereof, and more particularly related to maintaining color balance in the reduced toner application.
BACKGROUND OF THE INVENTION
In order to save the consumption of toner in color image duplicating devices such as printers, copiers, facsimile machines and any combinations thereof, the prior art color image duplicating devices utilize less than a predetermined amount of toner and generates color images at a low printing density in a toner save mode. In general, there are two kinds of approaches to save toner in image duplicating devices. According to one prior art toner saving method, image data is simplified or reduced. In another prior art toner saving method, a bias voltage for transferring toner onto a static image on a photoreceptor drum is reduced. The first prior art toner saving method loses resolution in a generated image, and a desired image is hardly obtained.
With respect to the second approach, color balance cannot be properly maintained at a bias voltage value that is lower than a predetermined optimal value for generating a desirable color image. Color toner generally includes a predetermined number of color components such as cyan (C), magenta (M) and yellow (Y), and these color components are layered to yield desirable colors. By reducing a bias voltage value for transferring, the original color balance is distorted since these color components of the toner are not equally or proportionately affected. Subsequently, an image generated at a low printing density is also distorted for human color perception. For example, a color toner application ratio among C, M and Y is 50:50:50 at a predetermined optimal bias voltage level. When the bias voltage is reduced, the color toner application ratio is altered to be 60:40:40. The change in the color toner application ratio is also affected by certain characteristics of toner and or a developing device. In the above example, since the C application percentage has increased prior to the reduction of the bias voltage, an image appears to be bluish in color, and no desired color is obtained in the image.
The above described second toner saving method needs to maintain color balance in an image generated at a reduced bias voltage value. Furthermore, it is also desirable to practice the toner saving mode based upon actual usage of toner in the image duplicating devices so that a tone cartridge lasts longer.
SUMMARY OF THE INVENTION
In order to solve the above and other problems, according to a first aspect of the current invention, a method of saving toner in image duplicating devices, toner having color components, including: selecting a reduced toner application level that is below a predetermined application level, the predetermined application level including information on a ratio of application levels of the toner color components, the ratio defining a toner application level ratio; determining a reduced toner application level ratio according to the selected reduced toner application level; adjusting the reduced toner application level ratio; and applying the toner based upon the adjusted toner application level ratio so as to generate a desired image maintain a consistent appearance of color image.
According to a second aspect of the current invention, a system for saving toner in image duplicating devices, toner having color components, including: an input unit for selecting a reduced toner application level that is below a predetermined application level, the predetermined application level including information on a ratio of application levels of the toner color components, the ratio defining a toner application level ratio; a processing unit connected to the input unit for determining a reduced toner application level ratio according to the selected reduced toner application level, the processing unit adjusting the reduced toner application level ratio; and an image generation unit connected to the processing unit for applying the toner based upon the adjusted toner application level ratio so as to generate a desired image maintain a consistent appearance of color image.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
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patent: 5083160 (1992-01-01), Suzuki et al.
patent: 5343282 (1994-08-01), Kazaki et al.
patent: 5355440 (1994-10-01), Sayanagi et al.
patent: 5722003 (1998-02-01), Suzuki et al.
patent: 5729270 (1998-03-01), Wright et al.
patent: 5737665 (1998-04-01), Sugiyama et al.
patent: 63-106763 (1988-05-01), None
patent: 8-137169 (1996-05-01), None
Brase Sandra
Knoble & Yoshida LLC
Ricoh Company, Ltd
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