Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1996-10-17
2001-04-24
Fuller, Benjamin R. (Department: 2855)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06220695
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to an ink-jet recording device, and particularly, to an electrostatic inkjet recording device in which a recording is achieved by controlling coloring particles in a pigmentary ink through the electrophoretic effect and discharging a jet of coloring particles by means of electrostatic force.
An example of such a recording device is shown in FIG.
1
. In
FIG. 1
, the ink-jet recording device comprises an ink chamber
201
filled with pigmentary ink, an electrophoretic electrode
203
for gathering the coloring particle
206
or charged toner around an ink discharge aperture
202
by means of the electrophoretic effect, and a discharge electrode
205
for discharging a jet of charged toner gathered around the ink discharge aperture toward a recording medium
204
to record on.
The ink chamber
201
is provided within a dielectric member
208
. The ink discharge aperture
202
is provided in the dielectric member
208
for communicating the inside and the out side of the ink chamber
201
. The discharge electrode
205
has a long and narrow form disposed in the ink discharging direction, and has its end pointed like a needle so as to facilitate electric field concentration on the end. The electrophoretic electrode
203
is fixed as one body on the side and back surfaces of the dielectric member
208
. A grounded facing electrode
214
is provided counter the ink discharge aperture
202
via the recording medium
204
. The pigmentary ink comprises petroleum organic solvent (isoparaffin) and coloring particles
206
of thermoplastic resin colored with electrification control agent or toner dispersed in the organic solvent. The toner is charged apparently positive by the zeta potential. The recording object
204
is ordinary paper. The electrophoretic electrode
203
and the discharge electrode
205
are connected to a voltage driver (not shown) for applying predetermined voltages with a polarity opposite from that of the coloring particle
206
to the electrodes
203
and
205
in predetermined timing.
FIG. 2
is a diagram showing the voltages applied to the electrophoretic electrode
203
and the discharge electrode
205
in printing operation of the recording device of FIG.
1
. In
FIG. 2
, if a constant voltage V
1
is applied to the electrophoretic electrode
203
as shown in
FIG. 2A
, forming an electric field in the ink chamber
201
filled with pigmentary ink, then the coloring particles
206
in the pigmentary ink moves at an electrophoretic speed toward the ink discharge aperture
202
by the action of the electric field, and eventually gathers around the ink discharge aperture
202
. If a pulse voltage V
2
with a duration of T
2
is applied to the discharge electrode
205
with the coloring particles
206
gathered around the ink discharge aperture, then a jet of coloring ink is discharged in synchronism with the pulse voltage V
2
from the ink discharge aperture
202
in the form of a flying particle group
207
, which adheres to the recording medium
204
. Subsequently, the electric field formed by the electrophoretic electrode
203
causes coloring particles
206
to be supplied to the ink discharge aperture
202
. Thus, the discharge of coloring particle is repeated, resulting in a formation of image on the recording medium
204
.
However, in the conventional ink-jet recording device as described above, the coloring particles
206
keep moving toward the ink discharge aperture
202
as long as the constant voltage VI shown in
FIG. 2
is applied to the electrophoretic electrode
203
. If no coloring particle
206
has been discharged from the ink discharge aperture
202
for a long time, then too many coloring particles will gathering around the ink discharge aperture
202
, causing an obstruction in the ink discharge aperture
202
. This prevents stable discharging of coloring particles
202
, having adverse influence on the quality of printed images.
The above and other problems in the prior art are solved and advances are made by the present invention. It is an object of the invention to provide an electrostatic ink-jet recording device for providing a stable printing by preventing too many coloring particles from gathering around the ink discharge aperture.
SUMMARY OF THE INVENTION
According to the invention, an electrostatic ink-jet recording device provides stable printing by preventing too much charged toner or too many coloring particles from gathering around an ink discharge aperture even if the charged toner has not been discharged for a long time. If the charged toner is not to be discharged, the potential difference between the electrophoretic electrode and the discharge electrode is controlled so as to suppress electrophoretic movement of the charged toner toward the ink discharging aperture, or the potential difference is made zero. This prevents the accumulation of too much toner around the ink discharge aperture. If the charged toner is to be discharged, the voltage applied to the discharge electrode is kept lower than the voltage applied to the electrophoretic electrode for a predetermined period of time before discharging a jet of the charged toner. This enables sufficient charged tone to gather around the ink discharge aperture.
REFERENCES:
patent: 4717926 (1988-01-01), Hotomi
patent: 0761441 (1997-03-01), None
patent: 2031344 (1980-04-01), None
patent: 56-167473 (1981-12-01), None
patent: 93 11866 (1993-06-01), None
patent: 9311866 (1993-06-01), None
Patent Abstract of Japan, JP-8-174815, Jul. 9, 1996 (NECCorp).*
European Examination Report issued Sep. 30 ,1999 in a related application (in English).
Hagiwara Yoshihiro
Minemoto Hitoshi
Shima Kazuo
Suetsugu Junichi
Uematsu Ryosuke
Dickens C.
Fuller Benjamin R.
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
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