Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
2000-03-07
2001-06-19
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C399S030000, C399S062000
Reexamination Certificate
active
06248496
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to a replenisher and a method of replenishing a xerographic device, particularly a xerographic device utilizing a hybrid scavengeless development system. More in particular, the invention relates to a method of determining optimal replenisher ratio to a xerographic device.
2. Description of Related Art
Historically, xerography has not been required to deliver prints of the same caliber as offset lithography. The offset lithography customer demands a level of print quality much higher than is available from conventional xerographic machines.
U.S. Pat. No. 5,545,501 describes an electrostatographic developer composition comprising carrier particles and toner particles with a toner particle size distribution having a volume average particle size (T) such that 4 &mgr;m≦T≦12 &mgr;m and an average charge (absolute value) pro diameter in femtocoulomb/10 &mgr;m (C
T
) after triboelectric contact with said carrier particles such that 1 fC/10 &mgr;m≦C
T
≦10 fC/10 &mgr;m characterized in that (i) said carrier particles have a saturation magnetization value, M
sat
, expressed in Tesla (T) such that M
sat
≧0.30 T, (ii) said carrier particles have a volume average particle size (C
avg
) such that 30 &mgr;m≦C
avg
≦60 &mgr;m, (iii) said volume based particle size distribution of said carrier particles has at least 90% of the particles having a particle diameter C such that 0.5 C
avg
≦C≦2 C
avg
, (iv) said volume based particles size distribution of said carrier particles comprises less than b % particles smaller than 25 &mgr;m wherein b=0.35×(M
sat
)
2
×P with M
sat
: saturation magnetization value, M
sat
, expressed in T and P: the maximal field strength of the magnetic developing pole expressed in kA/m, and (v) said carrier particles comprise a core particle coated with a resin coating in an amount (RC) such that 0.2% w/w≦RC≦2% w/w. See the Abstract. This patent describes that such developer achieves images of offset-quality in systems in which a latent image is developed with a fine hair magnetic brush. See column 4, lines 7-17.
It is known in the art to add additional toner and/or carrier materials to the housing of a xerographic device in order to replenish these materials depleted by the copying (image formation) process of the device. See, for example, U.S. Pat. No. 4,614,165, incorporated herein by reference in its entirety.
What is desired is a replenisher and an optimization of replenisher ratio (the ratio of toner to carrier in the replenisher) for each color developer to be used in forming a xerographic image with a xerographic device, particularly a device utilizing a hybrid scavengeless development scheme. Optimization of the replenisher ratio can enable the device to constantly and consistently produce images, particularly color images, exhibiting a quality analogous to that achieved in offset lithography.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a replenisher having a toner to carrier replenisher ratio that is optimized with respect to the properties of the toner and developer as well as the properties of the device in which the replenisher will be added.
It is a further object of the present invention to provide a method for optimizing the replenisher ratio of a replenisher in order to continuously achieve high, offset lithography quality images from a device to which the replenisher is added.
It is a still further object of the present invention to provide a device for forming images of offset lithography quality utilizing a hybrid scavengeless development system in which the developer for each color used in forming images with the device is replenished with developer having a preferred replenisher ratio.
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patent: 4935326 (1990-06-01), Creatura et al.
patent: 4937166 (1990-06-01), Creatura et al.
patent: 5227460 (1993-07-01), Mahabadi et al.
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patent: 5557393 (1996-09-01), Goodman et al.
patent: 5978633 (1999-11-01), Hirsch et al.
Steven C. Hart et al., “Trickle-Continuous Developer Material Replenishment for Two Component Development Systems”, The Sixth International Congress on Advances in Non-Impact Printing Technologies, pp. 44-54.
Angra Padam K.
Galloway Merrilee A.
Hollenbaugh, Jr. William H.
Silence Scott M.
Stamp Amy L.
Goodrow John
Oliff & Berridg,e PLC
Palazzo Eugene O.
Xerox Corporation
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