Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-12-14
2004-10-12
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06802596
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to improvement of an ink jet head spraying out ink by altering the volume of an ink channel formed at a piezoelectric member and a fabrication method of such an ink jet head.
2. Description of the Background Art
As conventional ink jet heads disclosed in, for example, Japanese Patent Laying-Open Nos. 63-252750 and 2-150355, an ink jet printer head having a plurality of parallel-arranged channels that can apply pressure onto the ink is proposed.
The aforementioned conventional art is superior in that an ink jet printer head that has nozzles at high density with a relatively simple structure can be realized. However, these heads had a problem in usage application from the standpoint of fabrication since it is necessary to form the channel constituted by many trenches at high density and establish electrical wiring from respective trenches.
As a method to solve such problems, Japanese Patent Laying-Open Nos. 4-307254, 6-218918 and 6-218934 propose the method of establishing electrical interconnection using a sealing member, wherein one end of a channel which is a trench is sealed by a soldering material, a coat, or a conductive member.
The conventional art will be described with reference to
FIGS. 30-33
.
Referring to
FIG. 30
, an ink jet printer head
1
includes a piezoelectric plate
27
, a cover plate
3
, a nozzle plate
31
, and a substrate
41
. Piezoelectric plate
27
is formed of a ceramic material of lead zirconate titanate (PZT) that has ferroelectricity. Piezoelectric plate
27
is subjected to a poling process in the direction of a polarization direction
5
.
Piezoelectric plate
27
has a plurality of trenches
8
formed by cutting and grinding through the rotation of a diamond cutting disk. These trenches
8
have the same depth and are arranged in parallel. A sidewall
11
which is the side plane of trench
8
is polarized in the direction of arrow
5
by the poling process.
At the inner plane of the sidewall of trench
8
, a metal electrode
13
is formed by vapor deposition. In the formation process of metal electrode
13
, piezoelectric plate
27
is positioned oblique to the vapor emitting direction indicated by the arrow from a target or vapor deposition source not shown, as shown in FIG.
31
. Upon emission of vapor, metal electrodes
13
and
10
are formed at the upper half of the side plane of trench
8
and at the top plane of sidewall
11
by the shadow effect of sidewall
11
.
Then, piezoelectric plate
27
is rotated 180 degrees, and metal electrodes
13
and
10
are formed in a similar manner. Thus, metal electrodes
13
and
10
are formed at the upper half of both side planes of trench
8
and the top face of sidewall
11
. Metal electrodes
13
and
10
are formed of aluminum, nickel, and the like.
Then, a conductive member
26
is embedded in trench
8
by a dispenser
25
(refer to FIG.
3
). Conductive member
26
is heated by a device not shown to be rendered solid. Conductive member
26
is formed in the vicinity of an end portion
15
of piezoelectric plate
27
. Trench
8
is filled entirely with conductive member
26
. Then, the excessive portion of conductive member
26
and metal electrode
10
at the top plane of sidewall
11
are removed by lapping or the like.
Cover plate
3
shown in
FIG. 30
is formed of a ceramic material or resin material and the like. Cover plate
3
has an ink inlet
21
and a manifold
22
formed by grinding, cutting or the like.
As shown by the sectional configuration of trench
11
of
FIG. 32
, the working side plane of trench
8
of piezoelectric plate
27
and the working side plane of manifold
22
are connected by an adhesive
4
of an epoxy type or the like. Accordingly, ink jet printer head
1
is constituted by a plurality of ink channels
12
spaced apart from each other laterally and having the top face of trench
8
covered. All ink channels
12
are filled with ink.
At the end plane of piezoelectric plate
27
and cover plate
3
, a nozzle plate
31
having a nozzle
32
provided corresponding to the position of each ink channel
12
is attached. Nozzle plate
31
is formed of plastic such as polyalkylene (for example ethylene), terepthalate, polyimide, polyetherimide, polyetherketone, polyethersulfone, polycarbonate, and cellulose acetate.
At the plane opposite to the working side plane of trench
8
of piezoelectric plate
27
, substrate
41
is attached by an epoxy type adhesive or the like. Substrate
41
is formed with a pattern
42
of a conductive layer corresponding to the position of each ink channel
12
. Pattern
42
of the conductive layer and conductive member
26
are electrically connected by wire bonding or the like.
Accordingly, metal electrode
13
located at one side plane of trench
8
and metal electrode
13
located at the other side plane are electrically connected by conductive member
26
. Therefore, when voltage is applied to conductive member
26
, voltage is applied at the same time to metal electrodes
13
at both sides of trench
8
through conductive member
26
, whereby sidewalls
11
corresponding to the side planes of trench
8
are deformed inwards of trench
8
to spray out ink droplets.
The operation of ink jet printer head
1
will be described with reference to
FIGS. 32 and 33
. A driving control circuit not shown determines the spray out of ink from ink channel
12
b
of ink jet printer head
1
according to predetermined data. Then, a positive driving voltage V is applied to metal electrodes
13
e
and
13
f
via conductive pattern
42
and conductive member
26
corresponding to relevant ink channel
12
b
, and metal electrodes
13
d
and
13
g
are connected to ground.
Referring to
FIG. 33
, a driving electric field is generated in the direction of arrow
14
b
at sidewall
11
b
whereas a driving electric field is generated in the direction of arrow
14
c
at sidewall
11
c
. Since driving electric field directions
14
b
and
14
c
are orthogonal to the polarization direction
5
, sidewalls
11
b
and
11
c
are rapidly deformed in the inner direction of ink channel
12
b
by the piezoelectric thickness slide effect. By this deformation, the volume of ink chamber
12
b
is reduced to rapidly increase the ink pressure. A pressure wave is generated to cause ink droplets to be sprayed out from nozzle
32
communicating with ink channel
12
b.
When application of driving voltage V is ceased, sidewalls
11
b
and
11
c
gradually return to their position previous to deformation. Therefore, the ink pressure within ink channel
12
b
is gradually lowered. As a result, ink is supplied into ink channel
12
b
via manifold
12
from ink inlet
21
.
Thus, the center portion of the two sidewalls
11
corresponding to respective side planes of trench
8
is caused to deform inwards of trench
8
simultaneously in order to spray out ink droplets.
In the above-described ink jet printer head
1
, end portion
15
of piezoelectric plate
27
blocked by conductive member
26
must be sealed completely so that ink will not be discharged from end portion
15
even when ink channel
12
is filled with ink.
In the case where conductive member
26
is formed at the trench end portion, phase-change from a liquid phase state to a solid phase state is required. The volume change caused by the phase change produces a void in conductive member
26
to result in ink leakage. Furthermore, in the case where complete sealing is not established, another member to occlude end portion
15
of trench
8
is required. This means that the fabrication method becomes more complicated.
It is noted that manifold
22
is provided at the trench attach plane of cover plate
3
. Since the ink supply opening by manifold
22
is provided during the path of the ink channel, the ink channel will become longer. Also, there is a problem that the ink channel resistance is increased since the flow is altered substantially perpendicularly at the ink channel from the ink supply opening.
Also, a longer ink channel cau
Higuchi Kaoru
Isono Hitoshi
Kakiwaki Shigeaki
Matoba Hirotsugu
Nakajima Yoshinori
Conlin David G.
Edwards & Angell LLP
Nguyen Judy
Roos Richard J.
Sharp Kabushiki Kaisha
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