Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-06-04
2001-12-18
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06331047
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink recording head, to a method of driving the ink recording head, and to an ink injecting method including the ink recording head to provide on record paper an output image capable of dealing with wide needs of from the printing industry where high-speed output of high quality image is requested to the printer industry based on office or personal request, and of the civil article industry requesting low-priced general output devices or the like using a variety of kinds and uses of record paper.
FIG. 10
shows an example of a method of driving an ink recording head used in a conventional electrostatic acceleration type ink jet recording system.
FIG. 10
is a perspective view of an ink recording head. In
FIG. 10
, a plurality of record electrodes
13
are installed in the head, a voltage is applied to an opposed electrode whose illustration is omitted in FIG.
10
and ink is injected by applying high voltage only to a selected electrode such that a potential difference between the selected electrode and the opposed electrode is increased. The electrodes
13
are divided into a number of electrodes between an upper plate
12
a
and a lower plate
12
b
to form ink supply ports
11
at predetermined intervals and are arranged as spacers. When ink (not shown) is injected into the ink supply port
11
, since the electrode
13
is wetted by the ink, the partitioned supply port
11
is concealed and the ink
2
forms continuous meniscus. Under such a continuous state, when high voltage pulses are applied while selectively scanning a plurality of the record electrodes
13
, an ink drop is injected only from a vicinity of a position of the electrode applied with the pulse voltage. (Refer to JP-A-56-167465)
However, in the record head and the recording method in the conventional electrostatic acceleration type ink jet recording system, there have been the following problems.
(1) When intervals among the plurality of record electrodes installed in the head are set to be sufficiently smaller than a distance between the head and the opposed electrode in order to obtain a high resolution, in carrying out printing, since a constant voltage pulse is applied only to the record electrode for injecting the ink, a large potential difference is produced between the selected record electrode and the nonselected record electrode and its influence becomes more significant than in respect of the opposed electrode. Since the record electrode supplies electric charge to the ink and the adjacent record electrodes are electrically connected via the ink, voltage drop is caused between the adjacent electrodes, a potential difference necessary for injecting the ink is not produced and there is a case in which the ink is not injected or the selectivity of the position of injecting the ink is deteriorated.
(2) Density of the ink injected from the head is determined by properties of the ink and in order to express an intermediary tone by changing the density, there has been only such means as for injecting the ink to the same position by a plural number of times, or expressing the intermediary tone by a magnitude of an area, or preparing several kinds of inks.
SUMMARY OF THE INVENTION
According to the invention, voltages are applied to a plurality of record electrodes and an opposed electrode not only by controlling a potential relationship between a selected record electrode among a plurality of the electrodes and the opposed electrode by switching, but also by controlling a relative potential relationship among the opposed electrode, the selected record electrode and a nonselected record electrode by switching such that a voltage having a polarity reverse to that of the opposed electrode is applied to the nonselected record electrode among the plurality of record electrodes installed at vicinities of an opening portion of a head.
In this way, by applying the voltages not only by controlling the potential relationship between the selected electrode and the opposed electrode among the plurality of record electrodes but also by controlling the relative potential relationship between the opposed electrode and the selected electrode as well as between the selected electrode and the nonselected record electrode, the voltages can be applied to the ink in consideration of the influence the adjacent electrodes of the plurality of record electrodes and the resolution is improved. Thus the problem that the ink is not injected or the selectivity of the position of injecting the ink is deteriorated as a result of narrowing the intervals of the electrodes installed in the head is resolved.
Further, by using an ink mixed with substances having two polarities, for example, an ink of a dispersing type in which a colorant is dispersed in a dispersion medium (electrostatic ink for an electrostatic plotter, or the like) and by inversing polarities of a relative potential relationship between -an opposed electrode and a selected electrode or between the opposed electrode and a nonselected electrode by the above-described ink injecting means or the like, density of the injected ink is made variable, so that such a problem can be resolved that since the density of the ink injected from the head is determined by properties of the ink, there has been only such means as for injecting the ink at the same position by a plural number of times in order to express an intermediary tone by changing the density.
REFERENCES:
patent: 4700204 (1987-10-01), Nakayama
patent: 0778134 (1997-06-01), None
patent: 0838335 (1998-04-01), None
patent: 9184930 (1997-07-01), None
Akase Atsuya
Kawaguchi Kouji
Kuwahara Seiji
Muramatsu Hiroyuki
Sato Tatsuru
Admas & Wilks
Gordon Raquel Yvette
Seiko Instruments Inc.
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