Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-12-01
2001-06-19
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S095000
Reexamination Certificate
active
06247801
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet printing process that utilizes solvent inks in the method of asymmetric heating drop deflection.
BACKGROUND OF THE INVENTION
Ink jet printers are well known in the printing industry. Ink jet printers are just one of many different types of printing systems that have been developed which include laser electrophotographic printers; LED electrophotographic printers; dot matrix impact printers; thermal paper printers; film recorders; thermal wax printers; dye diffusion thermal transfer printers. Ink jet printing has become recognized as a prominent contender in the digitally controlled, electronic printing arena because, e.g., of its non-impact, low-noise characteristics, its use of plain paper and its avoidance of toner transfers and fixing. However, there is an ongoing demand for improved digitally controlled printing systems that are able to produce high color images at a high speed and low cost using standard paper.
One such improvement is disclosed in copending U.S. patent application Ser. No. 08/954,317 entitled “Continuous Ink Jet Printer With Asymmetric Heating Drop Deflection” by Chwalek, et al., filed Oct. 17, 1997, the disclosure of which is hereby incorporated by reference. That application teaches an apparatus for controlling ink in a continuous ink jet printer that includes an ink delivery channel; a source of pressurized ink communicating with the ink delivery channel; a nozzle bore which opens into the ink delivery channel to establish a continuous flow of ink in a stream, the nozzle bore defining a nozzle bore perimeter; and a droplet generator which causes the stream to break up into a plurality of droplets at a position spaced from the ink stream generator. The droplet generator includes a heater having a selectively-actuated section associated with only a portion of the nozzle bore perimeter, whereby actuation of the heater section produces an asymmetric application of heat to the stream to control the direction of the stream between a print direction and a non-print direction. However, there is no disclosure of any specific inks in this application and the only specific fluid used in the example is water.
Another feature of that patent application is a process for controlling ink in a continuous ink jet printer that includes establishing a continuous flow of ink in a stream which breaks up into a plurality of droplets at a position spaced from the ink stream generator; and asymmetrically applying heat to the stream before the position whereat the stream breaks up into droplets to thereby control the angle at which the ink deflects.
Along with the development of ink jet printing systems, such as the system employing asymmetric heating drop deflection, is the requirement of inks useful in ink jet printing. An ink composition must be capable of meeting very stringent criteria to be useful in ink jet printing. Such properties of major concern of the ink composition are viscosity, surface tension, pH, density, conductivity, adhesive characteristics, wetting characteristics, drying rate and shelf life.
It is an object of this invention to provide an ink jet printing process employing a particular ink useful in a thermally-steered, continuous ink jet print head which provides a greater difference in deflection angle at which the ink deflects.
SUMMARY OF THE INVENTION
This and other objects are achieved in accordance with the invention which comprises an ink jet printing process comprising the steps of;
a) providing an ink jet printer in which a continuous stream of ink jet ink is emitted from a nozzle that is responsive to digital data signals;
b) loading the printer with an ink jet recording element;
c) loading the printer with an ink jet comprising an organic solvent; and
d) ejecting ink from a thermally-steered continuous ink jet print head onto one of the ink jet recording elements in response to the digital data signals.
By use of the process of the invention, ink jet prints are obtained using an ink in a thermally-steered, continuous ink jet print head which provides a greater difference in deflection angle at which the ink deflects.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the invention, the ink has a viscosity of from about 0.5 to about 50 centipoise at 20° C., preferably from about 1 to about 6 centipoise at 20° C. In another preferred embodiment of the invention, the continuous stream of ink has a deflection angle greater than that of water.
As noted above, the ink used in the invention is an organic solvent. Organic solvents which may be used include a substituted or unsubstituted monohydric alcohol, ester or ketone solvent, such as methanol, ethanol, 1-propanol, 2-propanol, 1-pentanol, 3-pentanol, 4-hydroxy-4-methy-2-pentanone, ethyl acetate, cyclohexanone, 2-butanone or acetone. The solvent may also be a hydrocarbon or halogenated hydrocarbon solvent, such as an isoparaffin, hexane, toluene, methylene chloride or 1,1,1-trichloroethane. The solvent used may also be a mixture of water and a substituted or unsubstituted polyhydric alcohol or glycol ether such as ethylene glycol, diethylene glycol, tetraethylene glycol, diethylene glycol n-butyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene n-propyl ether, ethylene glycol n-butyl ether, or diethylene glycol methyl ether. The solvent used may also be a mixture of water and a substituted or unsubstituted monohydric alcohol, ester, lactone, ketone, or cycloamide such as ethyl L-lactate, diacetone alcohol, 2-pyrolidinone, 1-methyl-2-pyrolidinone, hydroxyacetone, 2,2-dimethyl-1,3-dioxolane-4-methanol, butyrolactone or butoxyethanol. The solvent used may also be a sulfoxide, ether or hydroxyether.
When a mixture of an organic solvent and water is used, generally the organic solvent is present in an amount of from about 10 to about 90 percent of the mixture by volume.
As noted above, a continuous ink jet printer system that employs the method of asymmetric heating deflection is disclosed in the above-referred to U.S. Ser. No. 08/954,317. Following is a general description of the process employed. For specific details, please referred to the above-referred to U.S. Ser. No. 08/954,317. The system includes an image source such as a scanner or computer which provides raster image data, outline image data in the form of a page description language, or other forms of digital image data. This image data is converted to half-toned bitmap image data by an image-processing unit that also stores the image data in memory. A plurality of heater control circuits read data from the image memory and applies time-varying electrical pulses to a set of nozzle heaters that are part of a print head. These pulses are applied at an appropriate time, and to the appropriate nozzle, so that drops formed from a continuous ink jet stream will form spots on a recording medium in the appropriate position designated by the data in the image memory.
Recording medium is moved relative to a print head by a recording medium transport system, which is electronically controlled by a recording medium transport control system, and which in turn is controlled by a micro-controller. In the case of page width print heads, it is most convenient to move a recording medium past a stationary print head. However, in the case of scanning print systems, it is usually most convenient to move the print head along one axis (the sub-scanning direction) and the recording medium along an orthogonal axis (the main scanning direction) in a relative raster motion.
Ink is contained in an ink reservoir under pressure. In the non-printing state, continuous ink jet drop streams are unable to reach a recording medium due to an ink gutter that blocks the stream and which may allow a portion of the ink to be recycled by an ink recycling unit. The ink-recycling unit reconditions the ink and feeds it back to a reservoir. Such ink recycling units are well kno
Chwalek James M.
Romano, Jr. Charles E.
Trauernicht David P.
Cole Harold E.
Eastman Kodak Company
Tran Huan
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