Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2003-10-08
2004-07-27
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
Reexamination Certificate
active
06767092
ABSTRACT:
FIELD OF THE INVENTION
The invention relates in general to digital image recording and printing in an apparatus including an ink jet device for forming an ink image on a member. In particular, a coagulable ink is used in the ink jet device, coagulates are formed in the ink image on the member, excess liquid is removed from the coagulates while the coagulates remain on the member, and the coagulates are subsequently transferred to a receiver.
BACKGROUND OF THE INVENTION
High-resolution digital input imaging processes are desirable for superior quality printing applications, especially high quality color printing applications. As is well known, such processes may include electrostatographic processes using small-particle dry toners, e.g., having particle diameters less than about 7 micrometers, electrostatographic processes using nonaqueous liquid developers (also known as liquid toners) in which particle size is typically of the order of 0.1 micrometer or less, and ink jet processes using aqueous-based or nonaqueous inks. The less commonly used nonaqueous ink jet technology has an advantage over aqueous-based ink jet technology in that an image formed on a receiver requires relatively little drying energy and therefore dries relatively rapidly.
The most widely used high-resolution digital commercial electrostatographic processes involve electrophotography. Although capable of high process speeds and excellent quality printing, electrophotographic processes utilizing dry or liquid toners are inherently complicated, and require expensive, bulky, and complex equipment. Moreover, due to their complex nature, electrophotographic processes and electrophotographic machines tend to require significant maintenance.
Digital ink jet processes have the inherent potential to be simpler, less costly, and more reliable than digital electrophotographic processes. Generally, it is usual for ink to be fed through a nozzle, the diameter of which nozzle being a major factor in determining the droplet size and hence the image resolution on a recording surface. There are two major classes of ink jet printing, namely, continuous ink jet printing, and drop-on-demand ink jet printing. Continuous printing utilizes the nozzle to produce a continuous stream of electrically charged droplets, some of which droplets are selectively delivered to the recording surface, the remainder being electrostatically deflected and collected in a sump for reuse. Drop-on-demand ink jet printing produces drops from a small nozzle only as required to generate an image, the drops being produced and ejected from the nozzle by local pressure or temperature changes in the liquid in the immediate vicinity of the nozzle, e.g., using a piezoelectric device, an acoustic device or a thermal process controlled in accordance with digital data signals. In order to produce a gray scale image, variable numbers of drops are delivered to each imaging pixel. Typically, an ink jet head of an ink jet device includes a plurality of nozzles. In most commercial ink jet systems, aqueous-based inks containing dye colorants in relatively low concentrations are used. As a result, high image densities are difficult to achieve, image drying is not trivial, and images are not archival because many dyes are disadvantageously subject to fading. Moreover, the quality of an aqueous-based ink jet image is strongly dependent upon the properties of the recording surface, and will for example be quite different on a porous paper surface than on a smooth plastic receiver surface. By contrast, the quality of an electrophotographic toner image is relatively insensitive to the recording surface, and the toner colorants in both dry and liquid electrophotographic developers are generally finely divided or comminuted pigments that are stable against fading and able to give high image densities.
To overcome problems associated with fading and low image densities associated with dyed aqueous-based inks, pigmented aqueous-based inks have been disclosed in which a pigmented material is colloidally dispersed. Typically, a relatively high concentration of pigmented material is required to produce the desired highest image densities (Dmax). Exemplary art pertaining to pigmented aqueous-based inks includes the recently issued Lin et al. patent (U.S. Pat. No. 6,143,807) and the Erdtmann et al. patent (U.S. Pat. No. 6,153,000). Generally, pigmented inks have a much greater propensity to clog or modify the opening jet(s) of a drop-on-demand type of ink jet head than do dyed inks, especially for the narrow diameter jets required for high resolution drop-on-demand ink jet imaging, e.g., at 600 dots per inch. Drop-on-demand printers do not have a continuous high pressure in the nozzle, and modification of the nozzle behavior by deposition of pigment particles is strongly dependent on local conditions in the nozzle. In continuous ink jet printers using pigmented inks, the relatively high concentrations of pigment typically affects the droplet break-up, which tends to result in nonuniform printing.
Pigmented nonaqueous inks having particle sizes smaller than 0.1 micrometer for use in ink jet apparatus are disclosed in the Romano et al. patent (U.S. Pat. No. 6,053,438), and the Santilli et al. patent (U.S. Pat. No. 6,166,105).
Long-term stability (good shelf life) is an important property of both aqueous-based and nonaqueous colloidal dispersions useful for commercial ink jet inks. The principles of stabilization and destabilization are well documented for aqueous-based and nonaqueous colloids, such as for example in articles by B. J. Carroll in
Surface and Colloid Science,
Volume 9, pp. 1-68, (Wiley, 1976), by J. Th. G. Overbeek in
Colloidal Dispersions,
Special Publication No. 43, pp. 1-22, (The Royal Society of Chemistry, 1982), and D. H. Napper, ibid., pp. 99-128, and in the book by D. H. Everett,
Basic Principles of Colloid Science,
(The Royal Society of Chemistry, 1988). To prevent attractive dispersion forces (or Van der Waals forces) from producing flocculation and coagulation of colloidally dispersed particles, aqueous-based dispersions are typically electrostatically stabilized by electrostatic repulsions between the electrical double layers surrounding charged colloidal particles, and nonaqueous dispersions are typically sterically stabilized. A degree of steric stabilization can be important for certain aqueous-based colloids, which are primarily electrostatically stabilized. Similarly, a degree of electrostatic stabilization can be important for certain nonaqueous colloids, which are primarily sterically stabilized, such as for example a typical electrographic liquid developer. As described in the references cited above in this paragraph, electrostatically stabilized liquid dispersions may be destabilized by the addition of ionic salts, by changing the pH, by application of an electric field, and by heating or cooling. Sterically stabilized liquid dispersions may be destabilized by heating or cooling, by application of an electric field, by adding a non-solvent for the solution-embedded ends of sterically stabilizing polymeric moieties adsorbed to the colloid particle surfaces (i.e., adding a non &thgr;-solvent), or by adding an excess of stabilizing polymer. It is accepted usage to refer to flocs as precursors to coagulates, the flocs generally being loosely or reversibly bound, and the coagulates irreversibly bound. Herein below, both flocs and coagulates may be referred to as aggregates or agglomerates.
A deficiency associated with most high resolution conventional ink jet devices that deposit ink directly on to a (porous) paper receiver sheet is an unavoidable tendency for image spreading, with a concomitant resulting degradation of resolution and sharpness of the image produced. As a drop of deposited liquid ink is absorbed, capillary forces tend to draw the ink along the surface and into the microchannels between paper fibers, thereby causing a loss of resolution. Inasmuch as the colorant concentration of a dyed aqueous-based ink tends to be low, there is a c
Chowdry Arun
May John Walter
Tombs Thomas Nathaniel
Do An H.
Kessler Lawrence P.
Meier Stephen D.
Nexpress Solutions LLC
LandOfFree
Ink jet imaging via coagulation on an intermediate member does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink jet imaging via coagulation on an intermediate member, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet imaging via coagulation on an intermediate member will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3205896