Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-05-03
2003-02-04
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S096000
Reexamination Certificate
active
06513923
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet printing method which uses an ink jet ink set that provides images with improved color gamut.
BACKGROUND OF THE INVENTION
Ink jet printing is a non-impact method for producing images by the deposition of ink droplets in a pixel-by-pixel manner to an image-recording element in response to digital signals. There are various methods which may be utilized to control the deposition of ink droplets on the image-recording element to yield the desired image. In one process, known as continuous ink jet, a continuous stream of droplets is charged and deflected in an imagewise manner onto the surface of the image-recording element, while unimaged droplets are caught and returned to an ink sump. In another process, known as drop-on-demand ink jet, individual ink droplets are projected as needed onto the image-recording element to form the desired image. Common methods of controlling the projection of ink droplets in drop-on-demand printing include piezoelectric transducers and thermal bubble formation. Ink jet printers have found broad applications across markets ranging from industrial labeling to short run printing to desktop document and pictorial imaging.
The inks used in the various ink jet printers can be classified as either dye-based or pigment-based. A dye is a colorant, which is dissolved in the carrier medium. A pigment is a colorant that is insoluble in the carrier medium, but is dispersed or suspended in the form of small particles, often stabilized against flocculation and settling by the use of dispersing agents. The carrier medium can be a liquid or a solid at room temperature in both cases. Commonly used carrier media include water, mixtures of water and organic co-solvents and high boiling organic solvents, such as hydrocarbons, esters, ketones, etc. For aqueous dye-based inks, the dyes needs to be sufficiently soluble in water to prepare a solution that is capable of producing adequate density on the receiving element and stable for extended periods of storage without precipitation. High quality ink jet printing with dye-based inks requires dyes which will provide both bright hue and good light fastness.
To generate full color prints via ink jet printing, ink sets comprising at least cyan, magenta and yellow inks are normally utilized. In addition a black ink is often added to enhance the printing of text and darker colors. The range of colors that can be produced with a given set of inks defines the color gamut of that ink set. For the production of high quality photorealistic images via ink jet printing, ink sets with a large color gamut are preferred. In addition, it is important that the ink sets produce images with good fastness, especially to light.
The choice of the colorants in ink jet systems is critical for both light fastness and color gamut. The color gamut of an ink set is controlled primarily by the spectral absorption characteristics of the component dyes. The primary dyes (e.g., cyan, magenta and yellow) should only absorb light of the required wavelengths (i.e., have relatively narrow absorption bands) and not overlap excessively with the dyes in the complementary inks. While there are many dyes with bright hues that are useful in inkjet printing, many have poor light fastness. Conversely many light stable dyes suitable for ink jet printing have broad absorption bands and give dull colors and limited color gamut.
U.S. Pat. No. 6,183,548 relates to an inkjet ink set comprising a magenta ink, yellow ink and a cyan ink and an optional black ink. However there is a problem with this ink jet ink set in that the color gamut is not as large as one would like.
It is an object of this invention to provide an ink jet printing method using a set of inks capable of producing images which has a better color gamut than the ink sets of the prior art.
SUMMARY OF THE INVENTION
This and other objects are achieved in accordance with the present invention comprising an ink jet printing method, comprising the steps of:
A) providing an ink jet printer that is responsive to digital data signals;
B) loading the printer with an ink jet recording element;
C) loading the printer with an color ink jet ink set comprising:
(i) a magenta ink comprising a carrier and a water-soluble, transition metal complex of an 8-heterocyclylazo-5-hydroxyquinoline dye;
(ii) a yellow ink comprising a carrier and a water-soluble yellow dye;
(iii) a cyan ink comprising a carrier and a water-soluble cyan dye; and
(iv) an orange and/or green and/or violet ink comprising a carrier and a water-soluble orange and/or green and/or violet dye; and
D) printing on the image-receiving layer using the ink jet ink set in response to the digital data signals.
This printing method of the invention uses a color ink jet ink set which provides color gamuts suitable for pictorial imaging. A black ink can also be added to further increase the available color gamuts of this ink set.
DETAILED DESCRIPTION OF THE INVENTION
The ink sets used in the present invention are intended to be used in ink jet printers capable of printing four or more separate inks. At a minimum, cyan, magenta and yellow inks are required for full-color printing. The ink sets used in this invention include additional color inks that differ in hue from the cyan, magenta and yellow primaries; namely green, orange and/or violet. A black ink may be also be used to make text printing more efficient or to reduce overall ink lay-down when printing dark color areas.
The absorption characteristics of a given image dye will vary to some extent with a change in ink laydown or printed density. This is due to factors such as measurement flare, dye-dye interactions, dye-receiver interactions, dye concentration effects, and the presence of colored impurities in the media. However, by using characteristic vector analysis, sometimes referred to as principal component analysis or eigenvector analysis, one can determine a characteristic absorption curve that is representative of the absorption characteristics of the dye over the complete wavelength and density ranges of interest. The characteristic vector for each dye is thus a two-dimensional array of optical density and wavelength. This technique is described by Albert J. Sant in Photographic Science and Engineering, 5(3), May-June 1961 and by J. L. Simonds in the Journal of the Optical Society of America, 53(8), 968-974 (1963). Characteristic vectors thus derived can be used to calculate the color gamuts of ink sets described below as described in the above reference.
Dyes referred to by dye numbers are numbers assigned by The Color Index.
Any water-soluble yellow dye may be employed in the yellow ink of the ink jet ink set employed in the invention. In a preferred embodiment, the yellow dye is Direct Yellow 107, Direct Yellow 132, Direct Yellow 86 or mixtures thereof.
Any water-soluble cyan dye may be employed in the cyan ink of the ink jet ink set employed in the invention. In a preferred embodiment, the cyan dye is Acid Blue 9 or a water-soluble metal phthalocyanine dye such as Direct Blue 199 or Direct Blue 86 or mixtures thereof.
Any water-soluble black dye may be employed in the optional black ink of the ink jet ink set employed in the invention. In a preferred embodiment, the black dye is Reactive Black 31, Direct Black 19, Direct Black 168, Solubilized Sulfur Black or mixtures thereof.
The magenta inks employed in the invention may by formulated with one or more water-soluble, transition metal complexes of 8-heterocyclylazo-5-hydroxyquinoline dyes, represented by Structure 1 (below). These dyes are described in U.S. Pat. Nos. 5,997,622 and 6,001,161, the disclosures of which are hereby incorporated by reference:
wherein:
M represents a polyvalent transition metal ion;
L represents a neutral or anionic ligand;
each X, Y and Z independently represents a substituted or unsubstituted alkyl group of 1 to about 6 carbon atoms, a substituted or unsubstituted aryl group of about 6 to about 10 carbon atoms, a substituted or unsubstituted hetaryl group of abo
Evans Steven
Grady Barbara L.
Romano, Jr. Charles E.
Barlow John
Cole Harold E.
Eastman Kodak Company
Shah Manish S.
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