Electrophotography – Image formation – Development
Reexamination Certificate
2000-07-10
2001-09-18
Brase, Sandra (Department: 2852)
Electrophotography
Image formation
Development
C399S266000, C399S285000, C399S291000
Reexamination Certificate
active
06292643
ABSTRACT:
BACKGROUND OF THE INVENTION
Apparatus for mixing custom color toner for a color copier or printer using a traveling wave toner transport device, hereinafter referred to as a “device”, which mixes the colorants while transporting them to the photoreceptor.
In a typical color copier or printer, three color separations, cyan, magenta and yellow (CMY), can be used to create all colors in a final color print. However, while black can be generated by the use of these three colors, a better print will result if black toner is also used (CMYK) to produce the darker tones, resulting in four separations.
A further refinement is to use a custom color for special areas. For example, skin tones are difficult to reproduce in standard CMYK systems because, in any combination of toners, the separate colors are applied one on top of the other, and so a smooth blend of toner is difficult to produce. If a custom color is required it is typical to load pre-mixed toner into the printer and use it as an additional separation. However, this can be inconvenient since the custom color toner must be loaded into the printer before printing and removed after the run is complete.
What is needed is a system that can mix a custom color from the original CMYK toners and apply that to the photoreceptor.
SUMMARY OF THE INVENTION
This invention uses traveling wave toner transport devices to transport and mix toner. In its simplest form, a device is a belt made from insulating material on which is formed a lattice of conducting lines. Most of the lines are grounded but at regular intervals there are some that are held at a voltage. Further, each voltage is switched over time to adjacent lines, so that the overall effect is a voltage field that travels down the belt. Since the toner particles are themselves charged, they will be transported down the stationary belt as the voltage wave carries them. Such a device is described in U.S. Pat. No. 5,717,986 which is incorporated by reference herein.
A number of devices, one for each toner, are generally cylindrical in shape, round, oval or the like, and transport toner from each toner supply to an intermediate device in the form of a belt. The belt device carrying all of the colorants then transports the toner to the photoreceptor. A property of the traveling wave transportation process is that the various toners deposited on it are mixed as they are being transported. Thus, although the colorants are applied separately to the belt, they are fully mixed when they arrive at the photoreceptor, and so can be used as a custom color at that point. The result is that custom colors need not be pre-mixed and separately loaded into the printer for the additional separation.
REFERENCES:
patent: 5893015 (1999-08-01), Mojarradi et al.
patent: 6175707 (2001-01-01), Eklund et al.
Brase Sandra
Tran Hoan
Virga Philip T.
Xerox Corporation
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