Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-06-23
2002-08-20
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S100000
Reexamination Certificate
active
06435677
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet printing apparatus and an ink-jet printing method using the apparatus; more specifically, the invention relates to an ink-jet printing apparatus and an ink-jet printing method for carrying out printing of characters, images, or the like on a printing medium such as printing paper, OHP paper using an ink and a liquid which makes a coloring material in the ink insoluble (hereafter called a treatment liquid).
2. Related Background Art
The ink-jet printing method has various advantages such as low noise, a low running cost, capability of high speed printing, easiness of miniaturization of an apparatus, and easiness of colorization and is widely employed for printers, copying machines, or the like. For the printers, an ink to be employed is selected generally in consideration of the printing properties such as ejecting properties and fixing properties and printing qualities such as the bleeding of printed images, optical reflection density, and coloring ability. It is well known that inks can be divided into two types; a dye-based ink and a pigment-based ink; based on the coloring materials contained in inks. Of these, the pigment-based ink is superior in water resistance and light resistance to the dye-based ink and also has advantageous properties such as capability of clear character quality. On the other hand, as compared with the dye-based ink, the pigment-based ink takes time to be fixed on a printing medium and sometimes the abrasion resistance of obtained images after fixing is not sufficient, and depending on the ink ejected out of a nozzle by one ejecting operation, the size of ink dots formed on a printing medium tends to be small. That is, a pigment contained in a pigment-based ink is generally stably dispersed in the ink by mainly utilizing the electric repulsion force of is a polymer dispersant to cancel the intermolecular force which causes agglomeration of the pigment particles. A polymer dispersant is, therefore, necessary to be added to the ink corresponding to the amount of the pigment. In the case where such a pigment-based ink is employed for printing characters on plain paper by ink-jet recording process, owing to the penetration of the solvent, e.g. water, of the ink into the paper and evaporation of the solvent to ambient air, the pigment particles are agglomerated. At that time, the more the quantity of a polymer dispersant is added, the higher the agglomeration force of the ink on paper is heightened. Thus, the diameter of ink dots formed on a printing medium by a prescribed volume of an ink ejected out of an ink-jet head becomes small and the dot shape Is left approximately in a deformed shape formed at the time of impacting on the paper. Therefore, in order to obtain sufficient recording density to form images and ink dots with a dot diameter sufficient for recording without white stripes or the like, the ejection volume of an ink from an ink jet head is necessarily adjusted to be high. Even if such adjustment is carried out, jointly with the deterioration of the penetration property in paper attributed to the strong agglomeration force of pigment particles on which a polymer dispersant is adsorbed, fixation of an ink on a printing medium is delayed or the abrasion resistance of the recorded images is sometimes decreased.
In order to enlarge the dot diameter and improve the fixing property, it is considered to add a penetrant to an ink for the purpose of improvement of penetration properties of the ink In a printing medium. However, that is sometimes accompanied with undesirable phenomena such as deterioration of the dot shape (deterioration of the peripheral shapes of dots, so called feathering), penetration of the ink to the back side of paper (so called back-through) for the purpose of high quality recorded images. Further, since a coloring material penetrates into the inside of a printing medium, the optical density (OD) of ink dots is not so much increased even though the dot diameter becomes relatively large.
Furthermore, an ink containing a self-dispersing pigment has been proposed, and presumably because of weak agglomeration force of the pigment on paper as compared with that of the above described pigment dispersed in an ink by a dispersant, the ink can provide dots with an enlarged dot diameter but it is not yet sufficient.
As mentioned above, the studies are still on the way to develop a printing method and apparatus capable of providing at a satisfactorily high level various properties, e.g. fixing property of an ink, enlargement of the ink dot diameter, evenness of the density in ink dots, high optical density of ink dots themselves, or the like, which influence the quality of recorded images.
Meanwhile, with the purpose of further improvement of printing quality and image quality in the ink-jet printing technique (for example, improvement of water resistance and optical density (OD) of images on a printing medium), methods for providing an ink and a treatment liquid capable of reacting with the ink to a printing medium so as to cause a reaction of the ink and the treatment liquid with each other in the printing medium have been proposed and practically used.
Facts and Findings
The inventors of the present invention have studied the ink-jet printing technique in which a pigment-based ink and a treatment liquid capable of enacting with the pigment-based ink and capable of breaking the pigment dispersibility are employed in combination in order to solve the characteristic problems of a pigment-based ink and at the same time in order to utilize advantageous characteristics of the pigment-based ink. A recording process, in which a treatment liquid was applied so as to mix with a pigment-based ink on a printing medium in the liquid state either after or substantially at the same time of the application of the pigment-based ink onto the surface of the printing medium, was carried out as a part of the study. The quality of the resultant images was not necessarily satisfactory and in some cases the quality was rather found inferior to that of images formed using solely a pigment-based ink. Specifically, in the case where a pigment-based ink containing a pigment dispersed in an aqueous medium by a polymer dispersant was employed as a pigment-based ink in combination with a treatment liquid capable of reacting with the pigment-based ink, OD decrease attributed to the low area factor of the obtained ink dots was sometimes observed. The reason for occurrence of such a phenomenon is not clear, however, that is probably because the agglomeration of the pigment of the ink on the printing medium is significantly promoted by the treatment liquid. The area factor is, therefore, increased by increasing the shot-in ink quantity of a pigment-based ink to heighten OD, but in this case, fixing property is occasionally observed to be deteriorated.
A phenomenon
102
so called “exudation” or “haze” as shown in
FIG. 1
was sometimes observed in the dots (see
101
of
FIG. 1
) of a printing medium obtained by combining a pigment-based ink containing a self-dispersing pigment as a pigment-based ink with a treatment liquid to react with the pigment-based ink.
FIGS. 2A
,
2
, and
2
C illustrate the assumed mechanism of occurrence of this phenomenon.
When a pigment-based ink I
p
containing a self-dispersing pigment but not containing a polymer dispersant is applied to a printing medium P (especially plain paper or the like) (see
FIG. 2A
) and then a treatment liquid S is applied thereon, generation of a reaction product starts (see FIG.
2
B). As the reaction is proceeding, radial “exudation” occurs from approximately circular dots of the reaction product as illustrated in FIG.
2
C and “haze” surrounds the circumference of the dots. Such “exudation” or “haze” is regarded as having the appearance of the phenomenon known as feathering, so that it causes deterioration of the printing quality.
The above-described “exudation” or “haze” is assumed to be due to the followin
Koitabashi Noribumi
Tsuboi Hitoshi
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Shah Manish S.
LandOfFree
Ink-jet printing apparatus and ink-jet printing process... 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 printing apparatus and ink-jet printing process..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink-jet printing apparatus and ink-jet printing process... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2975544