Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-01-23
2001-03-06
Moses, Richard (Department: 2852)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S070000
Reexamination Certificate
active
06196664
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink droplet eject apparatus and method, and more specifically to an apparatus and method to eject a fine ink droplet suitable for graphic image printing on a printing medium.
2. Description of the Related Art
Various kinds of ink eject devices have been proposed, of which seven examples will described with reference to the accompanying drawings.
A first example shown in FIGS.
20
(A) and
20
(B) is an ink droplet eject apparatus for use in an ink jet printer or the like. As shown in FIG.
20
(A), a piezoelectric element
101
is vibrated so as to expand the volume of an ink accommodating chamber
102
. Liquid ink
103
is sucked from an ink tank (not shown). As shown in FIG.
20
(B), the volume of the ink accommodating chamber
102
is then reduced so as to apply a pressure to the ink
103
therein. An ink droplet
103
a
is ejected from a nozzle
104
onto a printing medium such as a paper. This art is described in U.S. Pat. No. 3,946,398.
The invention described in Japanese Patent Publication No. 61-59911/1986 is similar to that in U.S Pat. No. 3,946,398. In the Japanese publication, a heating element is contained in the ink droplet eject chamber. Heat energy causes a bubble to be instantaneously generated in the ink. An expansion force of the bubble causes the ink droplet to be ejected.
In the second example shown in
FIG. 21
, an ink fountain
202
is formed in a glass plate
200
. A piezoelectric element
201
is provided for drawing the ink
103
along a flow path
204
into the ink fountain
202
. Between a silicon board
205
and the glass plate
200
is disposed a dry film
206
which forms a space and a plurality of flow paths or the like. An eject heater
207
is heated. The heat energy causes a bubble to be instantaneously generated in the ink. The ink is ejected. This art is described in Japanese Patent Application Laid-open No. 5-112008/1993.
The second example is characterized in that inks having different dyestuff densities are supplied from a plurality of flow paths to the ink fountain
202
thereby allowing a density gradation.
Thus, in the above-described prior art, various ink droplet eject apparatuses using a pumping principle have been proposed.
On the other hand, ink droplet eject apparatus ejecting the ink in a mist state are described, for example, in Japanese Patent Application Laid-open No. 4-14455/1992, Japanese Patent Application Laid-open No. 4-299148/1992, Japanese Patent Application Laid-open No. 5-38810/1993, Japanese Patent Application Laid-open No. 4-355145/1992, and Japanese Patent Application Laid-open No. 5-508/1993.
A third example is disclosed in the above-listed Japanese Patent Application Laid-open No. 4-14455/1992.
In the third example, as shown in FIGS.
22
(A) and
22
(B), plural pairs of tandem electrodes
304
are formed at one end on a propagating surface
301
A of a piezoelectric propagating plate
301
. The electrodes
304
are used as drive means so as to apply a high-frequency alternating voltage E of about 20 MHz. The propagating surface
301
A is excited so as to generate a surface elastic wave (surface wave). In this drawing, numeral
302
denotes the ink fountain. Numeral
302
A denotes an ink flow path.
The generated surface elastic wave progresses in a direction shown by an arrow A. The surface elastic wave reaches a portion where the propagating surface
301
A is in contact with the liquid ink
103
. At this time, the surface elastic wave is transmitted to the ink
103
so as to be a longitudinal elastic wave (ultrasonic wave). This elastic wave causes an ink surface
307
exposed by a slit
306
to be excited. The ink droplet
103
a
is ejected in the mist state.
The fourth example shown in
FIG. 23
is disclosed in Japanese Patent Application Laid-open No. 5-508/1993. In
FIG. 23
, a gap is formed between a slit member
308
and a resonator
309
. An ink fountain
305
is disposed in the gap. Numeral
306
denotes a piezoelectric actuator.
In the fourth example, a capillary action initially causes the ink
103
to be filled in the ink fountain
305
. A resonance vibration is applied to the resonator
309
in a thickness direction. Its vibration energy is propagated to the ink
103
. Finally, random surface waves are formed on an ink interface
103
A of an ink eject port
310
. Interference of the surface waves causes an ink particle to be ejected in the mist state in accordance with a vibration frequency of the resonator
309
.
The fifth example shown in
FIG. 24
is disclosed in Japanese Patent Application Laid-open No. 5-38810/1993. In the fifth example, a pair of electrodes
403
A and
403
B are formed on both surfaces of a piezoelectric substrate
401
. A nozzle plate
405
is joined to the piezoelectric substrate
401
via a gap support member
404
. Capillary action causes the liquid ink
103
to be filled in the gap space.
An intersection region
406
is formed by the electrodes
403
A and
403
B. To the intersection region
406
is applied a voltage displaced by a resonant frequency determined by the thickness of the piezoelectric substrate
401
. The piezoelectric substrate
401
is resonated so as to generate the ultrasonic wave in the liquid ink
103
.
The generated ultrasonic wave is propagated in the ink
103
. The surface wave is generated on the ink surface
103
A of the ink
103
filled in a nozzle
405
A just over the intersection region
406
. When an amplitude of the surface wave is larger than the constant amplitude, the ink droplet
103
a
is discharged in the mist state.
Furthermore, a similar technique is also disclosed in Japanese Patent Application Laid-open No. No. 4-14455/1992, Japanese Patent Application Laid-open No. 4-299148/1992, Japanese Patent Application Laid-open No. 4-355145/1992, Japanese Patent Application Laid-open No. 5-508/1993 and Japanese Patent Application Laid-open No. 5-38810/1993. However, their means for generating the surface wave on an ink liquid surface are different from one another.
In any apparatus using as its ejecting principle an ultrasonic wave wetting apparatus, the surface wave is generated at random on a free surface of a liquid. The interference of the surface wave causes the ink droplet
103
a
to be ejected in the mist state from many unspecified ejecting points.
In addition, a sixth example shown in
FIG. 25
is an ink droplet eject apparatus using an acoustic pressure by an acoustic streaming. It is disclosed in Japanese Patent Application Laid-open No. 63-162253/1988.
In this technique, as shown in
FIG. 25
, the vibration of a piezoelectric transducer
501
causes an ultrasonic acoustic wave to be generated. The ultrasonic acoustic wave is focused on one point on the free surface
103
A of the ink
103
by a concave spherical surface acoustic lens portion
502
A formed on an end surface (upper end surface in
FIG. 25
) of an acoustic lens body
502
. When the acoustic wave collides with the free surface
103
A of the ink
103
, a radiation pressure is generated. The generated radiation pressure causes the ink droplet
103
a
to be ejected separately from the free surface
103
A of the ink
103
.
A seventh example shown in FIGS.
26
(A) and
26
(B) is an ink droplet eject apparatus using acoustic pressure by an acoustic streaming, as is the case with the sixth example described above. The seventh example is disclosed in Japanese Patent Application Laid-open No. 6-218926/1994.
In the ink droplet eject apparatus shown in
FIG. 25
, a plurality of piezoelectric elements
601
are disposed in a matrix. A predetermined voltage is applied to a group of piezoelectric elements
601
in a portion where the ink droplet is to be ejected. A concavity
602
is formed in order to concentrate a pressure wave. A high frequency voltage is then applied to the concavity so as to vibrate the concavity. This causes the ink droplet
103
a
to be ejected. Numeral
604
denotes the ink surface. Numeral
605
denotes an ink film layer. Reference character A denotes a direction of ink fl
Kanda Torahiko
Kojima Ryuichi
Otsuka Yasuhiro
Moses Richard
NEC Corporation
Young & Thompson
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