Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-10-27
2001-12-11
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06328426
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer device which causes to fly or travel ink containing charged pigment particles through an electric field.
2. Conventional Art
The following ink discharge methods for an ink jet recording device which forms pixels on a recording medium by blowing liquid ink drops were known:
(1) an electro and thermal conversion method in which ink is discharged from a nozzle by making use of pressure of bubbles caused by heating the ink through a heating element.
(2) an electro static method in which insulative ink solvent is polarized by an electric field or conductive ink solvent is electro-statically pulled out. JP-B-56-9429 discloses an ink jet recording device using the electro and thermal conversion method, and JP-A-56-4467 and JP-A-8-174815 disclose ink jet recording devices using the electro static method.
However, the ink jet recording device as mentioned above using the electro and thermal conversion method is not suitable for a gradation recording, because the ink discharge amount does not depend on the applied voltage. Further, although it is necessary to provide respective heating elements for respective nozzles, it is difficult to arrange the nozzles in high density. Moreover, if the diameter of the nozzle aperture is reduced in order to improve resolution, the nozzle aperture tends to clog due to solidification of the ink which reduces discharge stability of the ink.
On the other hand, in the ink jet recording device as mentioned above using the electro static method, since the ink discharge amount sensitively responds to a variation of electric field near the top of the respective nozzles, the ink discharge amount tends to unstabilize. Further, when a conductive ink is used, it is necessary to avoid a mutual action between flying liquid ink drops by limiting discharge frequency of the ink from the nozzles which reduces recording speed.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a printer device which shows an excellent discharge stability of ink and further permits a highly accurate and high gradation recording with a high speed.
A printer device according to the present invention which achieves the above object and in which a plurality of discharge electrodes are provided in a slit to which ink containing charged pigment particles is supplied, an electric field is formed between the plurality of discharge electrodes and an opposing electrode opposing to the plurality of discharge electrodes, and liquid ink drops are caused to fly from top ends of the plurality of discharge electrodes toward the opposing electrode, is characterized in that the charged pigment particles contained in the ink are caused to aggregate at the top end portions of the respective discharge electrodes and liquid ink drops, each containing more than 50 vol % of the aggregates of the charged pigment particles, are caused to fly.
Further, the printer device according to the present invention can cause to aggregate the charged pigment particles contained in the ink and cause to fly the liquid ink drops each containing the aggregates of the charged pigment particles, if at least one of the following four conditions is satisfied:
(1) diameter of a print dot is about 1 &mgr;m~10 &mgr;m;
(2) a pulse electric field applying means is provided between the respective discharge electrodes and the opposing electrode and the pulse electric field applying means further includes a control means which varies the diameter of the print dot by varying a pulse voltage and pulse width;
(3) partition members for guiding ink stream are provided at both sides of the respective discharge electrodes, and the top ends of the partition members (the top ends from which the liquid ink drops flow out) are restricted; and
(4) the top ends of the respective discharge electrodes are restricted in a triangle shape in order to concentrate electric field at the top ends of the respective discharge electrodes, the restricted top end angle is selected less than 90°, and preferably to be 30°~70°.
The ink used preferably satisfies at least one of the following two conditions:
(1) charged amount per unit mass of the charged pigment particles is 10~200 mC/g and, the charged pigment having particle radius of 0.1~5 &mgr;m is contained in 2~10 vol %; and
(2) at least two kinds of charged pigment particles having different charged amount per unit mass and different particle diameter are included.
According to the present invention, a printer device can be realized which shows a high ink discharge stability and permits a highly accurate, fine and high gradation recording with a high speed.
REFERENCES:
patent: 0 703 080 A2 (1996-03-01), None
patent: 0 761 441 A2 (1997-03-01), None
patent: 0 869 004 A2 (1998-10-01), None
patent: 54-51837 (1979-04-01), None
patent: 56-4467 (1981-01-01), None
patent: 08-174815 (1996-07-01), None
patent: WO 93/11866 (1993-06-01), None
Chahn Lee
Fujiwara Shigetaka
Imazeki Shuji
Nagae Yoshiharu
Shinohara Hideki
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Tran Huan
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