Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2003-01-13
2004-09-07
Eickholt, Eugene H. (Department: 2854)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S100000, C347S101000, C428S195100
Reexamination Certificate
active
06786587
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an ink-jet printing apparatus and a printing method. More particularly, the invention relates to an ink-jet printing apparatus and a printing method performing printing of characters, images and the like on a printing medium, such as a printing paper, an OHP film and the like using an ink and a liquid which makes a coloring material in the ink insoluble (hereinafter also referred to as a treatment liquid).
2. Description of the Related Art
A treatment liquid of this kind reacts with a coloring material contained in an ink, such as a pigment, dye and the like and makes the coloring material insoluble. In ink-jet printing technology, in general, the treatment liquid is ejected to overlay the portion of the printing medium where the ink is ejected or in the vicinity thereof, for admixing the ink and the treatment liquid to cause a reaction. Then, as a result of the reaction, the coloring material of the ink is fixed on the surface of the printing medium or penetrating into the printing medium for achieving water resistance of the printing product.
It has also been known that action for making the coloring material in the ink insoluble also serves for limiting penetration of the pigment or dye in a surface layer of the printing medium, to result in improvement of an optical density of the printing medium (hereinafter occasionally simply referred to as “OD value”).
However, in the conventional ink-jet printing technology using the foregoing treatment liquid, it has been newly recognized by the inventors that there have been respective problems with the coloring materials to be employed in the ink for improving printing quality.
When a dye is used as the coloring material, a first problem that has been encountered is that a sufficiently high OD value cannot be obtained even when the dye and the treatment liquid react. This is because that the dye per se cannot develop a relatively low OD value as used for printing. Therefore, even if the treatment liquid and the dye are reacted to fix most of the dye in the surface layer of the printing medium as above-mentioned, the OD value is as high as the case where pigment is used as the coloring material.
The second problem the inventors have encountered with the dye is a phenomenon called “overflow” or “sweep”, blurring an edge portion of a printed image.
FIGS. 1A
to
1
D are illustrations for explaining this phenomenon. As shown in
FIG. 1A
, when an ink I
d
using a dye as a color agent, is deposited on the lower penetrative printing medium P, such as a plane paper, by ejection of the ink through a printing head as an ejecting portion, a part of the ink penetrates into the printing medium and the remaining part of the ink is present in a liquid state on the surface of the printing medium P. Then, as shown in
FIG. 1B
, in the similar manner, a treatment liquid S is deposited over the ink I
d
to cause a reaction in the boundary between the treatment liquid S and the ink I
d
, by ejection through the printing head. As shown in
FIG. 1C
, a part of a reaction product flows out to the circumference of the ink I
d
and flows into the lower side of the ink I
d
. Then, a reaction between the dye in the ink I
d
and the treatment liquid S gradually progresses. Finally, an ink dot consisting of the reaction product of the dye and the treatment liquid is formed as shown in
FIG. 1D
The ink dot thus formed has a contour portion where the ink flows over a contour of the dot.
According to a prediction by the inventor, the foregoing phenomenon is caused by the flow of a gel from a high viscous reaction product in the ink and the treatment liquid for a relatively low reaction speed between the dye and the treatment liquid.
Flowing out of the ink in the ink dot shown in
FIG. 1D
due to such phenomenon makes a contour blur at the edge portion of an image, and appears as a so-called “overflow” to cause degradation of the printing quality. Fluidizing of the foregoing reaction product also causes “sweeping” of the reaction product in the direction of the relative speed between the fed printing medium and the printing head for the treatment liquid. For this reason also, it has been predicted that the edge portion of the printed image becomes blurry.
The second problem concerning the dye set forth above may not occur where only dye ink is used and the treatment liquid is not used in printing. Accordingly, where printing is performed using the dye ink and the treatment liquid which makes the dye ink insoluble, this particular technical problem is encountered.
Moreover, even if printing is performed using an ink including a pigment as the coloring material and the treatment liquid therefor, a particular problem caused by the reaction between the ink and the treatment liquid will be explained hereinafter.
The pigment ink per se exhibits a relatively high OD value as used for printing. By reaction with the treatment liquid, owing to the effect of the treatment liquid set forth above, the OD value of the pigment ink can be improved. In comparison with the foregoing dye, the pigment has a high reaction speed with the treatment liquid.
However, as the first program in the case where pigment is used, the inventors have found a problem they call “crack”. Namely, when reaction of the pigment ink and the treatment liquid is caused especially on the film-like printing medium for an OHP, since the reaction speed of the pigment with the treatment liquid is high as set forth above, most of the pigment coagulates on the surface before penetration into the printing medium. Furthermore, owing to the property of the pigment, the pigment may coagulate strongly. Therefore, after a solvent in the ink once penetrates into the printing medium and is fixed therein, the coagulated reaction product set forth above will become relatively large individual blocks due to the coagulation force to form gaps not filled in by the reaction product between these individual blocks. This phenomenon is perceived as a “crack” upon observing the recording medium visually to degrade the quality of the printed image. When the foregoing reaction product is not filled in, the surface of the printing medium is exposed, to lower the OD value of the overall printed image.
Pigment ink includes an ink using a dispersant, such as a resin, a surface-active agent and the like, in order to stabilize dispersion of the pigment in the ink solvent (hereinafter occasionally referred to as dispersant-containing pigment ink), and an ink using a self-dispersion type pigment and containing no dispersant (hereinafter occasionally referred to as no dispersant containing pigment ink). The second problem concerning pigment ink is cause in the case where the latter no dispersant containing pigment ink and the treatment liquid are used.
The inventor has observed the phenomenon called “soaking out” or “blur” in a dot formed on the printing medium using the no dispersant containing pigment ink and the treatment liquid.
FIGS. 2A
to
2
C are illustrations for predictively explaining this phenomenon.
After the application of the no dispersant containing pigment ink I
p
on the printing medium P such as plain paper (see FIG.
2
A), the treatment liquid is applied in an overlaying manner (see FIG.
2
B). Then, production of reaction product is initiated, at first, from the reaction between the ink and the treatment liquid. Then, according to progress of this reaction, radial “soaking out” is caused from a substantially circular dot of the reaction product to “blur” the entire circumference of the dot (see FIG.
2
C). Such “soaking out” or “blur” appears similar to known feathering. Accordingly, the printing quality is lowered.
The foregoing “soaking out” or “blur” is inferred as the following phenomenon chemically or in micro view. The no dispersant containing pigment ink has a relatively high reaction speed in reaction-with the treatment liquid. Therefore, the dispersed pigment instantly causes dispersion breakage to generate cluster
Canon Kabushiki Kaisha
Eickholt Eugene H.
Fitzpatrick ,Cella, Harper & Scinto
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