Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-02-11
2002-08-20
Barlow, John (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S034000, C347S021000
Reexamination Certificate
active
06435648
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a head unit, an ink-jet cartridge and a liquid ejection apparatus. Particularly, the invention relates to an ink-jet head unit, an ink-jet cartridge and an ink-jet printing apparatus for performing,printing with ejecting an ink and a printing ability improving liquid (hereinafter simply referred to as “processing liquid”) which makes a coloring material in the ink insoluble or coagulates the coloring material.
The present invention is applicable for all of devices or apparatuses which employ a paper, a cloth, a leather, a non-woven fabric, an OHP sheet and so forth, and even a metal and so forth as media (hereinafter simply referred to as “printing medium”) receiving inks and the printing ability improving liquid. Concretely, the present invention is applicable for an office machine, such as a printer, a copy machine and a facsimile machine, an industrial production machine and so forth.
2. Description of the Related Art
Conventionally, an ink-jet system has been widely used in a printer, a copy machine and so forth due to its advantages of low noise, low running cost, compactness of the apparatus, and ease of color printing.
However, in a printing apparatus employing such ink-jet system, if a printing medium called plain paper is used, bleeding occurs on the printing medium upon deposition of water or so forth due to insufficiency of resistance of a printed image to water. Also, upon color printing on the plain paper, it has not been possible to achieve both of a high density image without causing feathering and an image without bleeding between colors. Therefore, it may be possible that a color image with sufficient fastness property or satisfactorily high print quality cannot be obtained.
As a solution for the problem set forth above, an ink providing water resistance for a coloring material contained in the ink has been recently put into practice. However, the water resistance of the ink is still insufficient. Also, such water resistive ink is difficult to dissolve in water after once dried in principle, and it has a tendency to easily cause plugging in ejection openings or so forth in an ink-jet printing head. On the other hand, a construction of the apparatus required for preventing plugging of the ejection openings becomes complicated.
Also, there have been various proposals for improving fastness property of the printed products.
For example, Japanese Patent Application Laid Open No. 24486/1978 proposes subjecting a printed product to a post treatment for converting a dye into a lake for fixing in order to enhance color fastness against wetness of the printed product.
On the other hand, Japanese Patent Application Laid-open No. 43733/1979 discloses a method for performing printing with employing a substance containing two or more components which increases a layer forming ability by contacting with each other under room temperature or heated condition, in the ink-jet system. In this method, a printed product having a layer firmly fixed on the printing medium can be obtained by contacting the components on the printing medium.
Also, Japanese Patent Application Laid-open No. 150396/1980 discloses a method for, after printing, applying an agent for making the dye water resistant to a water based ink so as to react with the dye in the ink to form a lake.
Furthermore, Japanese Patent Application Laid open No. 128862/1983 discloses an ink-jet printing apparatus for performing printing by preliminarily recognizing positions on which dots are formed and by providing a printing ink and a processing ink on the recognized positions in overlaying manner. Here, enhancement of water resistance of the printing product has been attempted by ejecting the processing ink in advance of ejection of the printing ink, conversely by ejecting the processing ink over the preliminarily ejected printing ink, or by ejecting the printing ink after overlaying the printing ink on the preliminarily ejected processing ink.
On the other hand, it has been well known that the ink-jet printing system encounters the following problem.
At first, in the ink-jet system, a fine ink droplet which is much smaller than an ink droplet to be ejected may be generated associated with ejection of the ink droplet. Further, a fine liquid droplet may be generated when the ink droplet ejected rebounds on the printing medium. These liquid droplets will occasionally form a mist of fine liquid droplets, and such mist may deposit on a surface of an ink-jet head on which an ejection opening is formed. When a large amount of the mist is deposited around the ejection opening, or when paper dust or other foreign matter adheres on the mist deposited around the ejection openings, ink ejection can be affected, causing variation in the ejecting direction of the ink droplet (hereinafter also simply referred to as “deflection”), failure of ejection of the ink droplet and so forth.
Secondly, in the ink-jet head, while ejection is not performed, particularly when a non-ejection state is maintained for a long period, viscosity of the ink in the ejection openings can increase and the ink can solidify. Also in this case, deflection, ejection failure or so forth can be caused.
It has been known that the following construction is provided in the ink-jet printing system for avoiding the foregoing inconvenience.
Concerning the first problem, in order to prevent the mist from depositing on non-specified portions of the ink-jet head, improvement of the head per se or introduction of air flow generated by a blower fan into a gap between the head and the printing medium are attempted, for example. By the effect of the former, reduction of the amount of the mist to be generated can be observed. However, in the latter case, since the flying direction of the ejected ink droplet can be disturbed by the air flow, the air flow has to be relatively weak and then the weakness of the air flow can cause the mist deposit prevention to be insufficient.
Furthermore, it is also known to deposit the ink mist to a predetermined region by applying an electric field to the ink mist per se. The fine ink droplets forming the ink mist may not be polarized at specific polarity upon separation into the fine droplets, and also, a non-polarized ink droplet may be generated. As a result, control of the ink mist deposit region by the electric field cannot be performed effectively.
In addition, as a means for cleaning and removing the ink, paper dust or so forth once deposited on an ejection opening forming surface of the head due to generation of the ink mist, it has been generally known to wipe the ejection opening forming surface, using a blade made of an elastic material, such as rubber or so forth.
Concerning the second problem, it has been known to cover the ejection opening forming surface with a cap while not printing, so as to prevent the ink from evaporating and drying, so that increasing of viscosity and solidification of the ink in the ejection opening of the ink-jet head can be prevented. Also, if the ejection failure is caused by increasing of viscosity or solidifying of the ink, or if foreign-matter that cannot be removed by the blade which is set out with respect to the first problem, resides on the ejection opening forming surface, normal ejection is recovered by suctioning the ink of increased viscosity in the ejection opening or the ink deposited on the ejection opening forming surface with a suction pump connected to the cap, so as to expel the ink of increased viscosity or so forth.
Furthermore, in printing operation of an on-demand type ink-jet printing system, while it depends on the printing data, not all of a plurality of ejection openings provided on the head are used for printing in most cases. Therefore, some ejection openings may not be used for a predetermined period or longer. Also, in the case where an ink-jet head is provided for each color, such as in a color printing apparatus, depending on printing color, printing data may be not transferred (ejection of
Koitabashi Noribumi
Murakami Shuichi
Nakajima Yoshinori
Uetsuki Masaya
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hsieh Shih-wen
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