Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-05-08
2004-03-09
Meier, Stephen D. (Department: 2863)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06702432
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inkjet head for an office and industrial use.
2. Related Art
FIG. 1
is a cross-sectional view of a conventional inkjet head
200
. As shown in
FIG. 1
, the inkjet head
200
includes an orifice plate
2
, a chamber plate
4
, a restrictor plate
6
, a diaphragm plate
9
, a support plate
17
, and a housing
11
, which are all fixed one on the other in this order by adhesive. The inkjet head
200
further includes a plurality of laminated-type piezoelectric elements
12
and a fixing plate
13
for supporting the piezoelectric elements
12
.
As shown in
FIGS. 1
to
3
, the orifice plate
2
is formed with a plurality of nozzles
1
through which ink droplets are ejected. The chamber plate
4
is formed with a plurality of pressure chambers
3
in fluid communication with the corresponding nozzles
1
. The restrictor plate
6
is formed with a plurality of restrictors
5
that regulate ink flow toward the pressure chambers
3
. The diaphragm plate
9
is integrally formed with a filter
8
. The support plate
17
is formed with a plurality of through holes
10
A and
10
B larger than a cross-sectional dimension of the piezoelectric element
12
.
The housing
11
is formed with a common ink chamber
16
and an opening
18
. The common ink chamber
16
is in fluid communication with all the restrictors
5
via the through holes
10
B and the filter
8
. The opening
18
is greater than a cross-sectional dimension of the fixing plate
13
. A pair of positioning holes
14
are formed through all the orifice plate
2
, the chamber plate
4
, the restrictor plate
6
, the diaphragm plate
9
, the support plate
17
, and the housing
11
for positioning these members when manufacturing the inkjet head
200
. Adhesive agent or the like (not shown) is filled in the positioning holes
14
to fix the members.
As shown in
FIG. 2
, portions of the diaphragm plate
9
corresponding to the through holes
10
A formed in the support plate
17
serve as diaphragms
7
. Each piezoelectric element
12
is attached to the corresponding diaphragm
7
through the through hole
10
A such that the piezoelectric element
12
confronts the pressure chamber
3
via the diaphragm
7
.
In this configuration, ink inside the common ink chamber
16
is distributed to the restrictors
5
and supplied into the pressure chambers
3
. Upon application of a driving voltage, the piezoelectric element
12
causes displacement in the diaphragm
7
, which in turn decreases the volume of the corresponding pressure chamber
3
with a resultant increase in the internal pressure thereof. This internal pressure ejects ink inside the pressure chamber
3
as an ink droplet through the nozzle
1
.
SUMMARY OF THE INVENTION
However, in the above configuration, when the inkjet head
200
is produced by adhering all the plates
2
,
4
,
6
,
9
,
17
at the same time, and adhered portion
9
e
of the diaphragm plate
9
(
FIG. 4
) is not securely adhered to the support plate
17
for the reason that a uniform pressing force is not applied to the adhered portion
9
e
in a direction indicated by an arrow in
FIG. 4
due to the restrictor
5
located adjacent to the adhered portion
9
e
. Accordingly, there is a danger that the diaphragm plate
9
is adhered to, for example, only a region between points P
2
and P
3
of the support plate
17
, although the diaphragm plate
9
must be adhered to a region between points P
1
and P
3
. This changes a fixed end of the diaphragm from the original point P
1
to the point P
2
, changing the dimension of the diaphragm
7
. Unevenness in the position of the fixed ends of the diaphragms
7
varies the deforming amount of the diaphragms
7
, and changes ink ejection performance of the nozzles
1
, whereby overall ink ejection performance of the inkjet head
200
is degraded.
Further, if adhesion between the adhered portion
9
e
and the support plate
17
is insecure, when the piezoelectric element
12
deforms the diaphragm
7
in response to a driving voltage, the adhered portion
9
e
will be easily peeled off the support plate
17
, further shifting the fixed end of the diaphragm
7
over a long time use.
It is an object of the present invention to overcome the above problems, and to provide an inkjet head realizing a uniform ink ejection performance.
In order to overcome the above and other object, there is provided an inkjet head including a diaphragm plate having a first surface and a second surface, a piezoelectric element attached to the first surface of the diaphragm plate for selectively deforming the diaphragm plate, a support plate attached to the second surface of the diaphragm plate and formed a first through hole and a second through hole, and a channel plate attached to the support plate in a manner that the support plate is interposed between the channel plate and the diaphragm plate, the channel plate being formed with a channel fluidly connecting the first through hole and the second through hole.
There is also provided an inkjet head including a pair of support plates formed with a through hole, a diaphragm plate interposed between and attached to the pair of support plates, and a piezoelectric element attached to the diaphragm through the through hole formed in one of the support plates. The support plates are substantially identical.
Further, there is provided an inkjet head including a support plate, a diaphragm plate, and a piezoelectric element. The support plate is formed with a through hole. The diaphragm plate is attached to the support plate. A portion of the diaphragm plate corresponding to the through hole serves as a diaphragm. The diaphragm has a first surface confronting the through hole and a second surface opposite to the first surface. The piezoelectric element is attached to the second surface of the diaphragm for selectively deforming the diaphragm.
REFERENCES:
patent: 5831651 (1998-11-01), Usui et al.
patent: 5912526 (1999-06-01), Okawa et al.
patent: 5988799 (1999-11-01), Abe et al.
patent: 6382781 (2002-05-01), Furuhata et al.
patent: 6488367 (2002-12-01), Debesis et al.
patent: 6530652 (2003-03-01), Kim et al.
Kashimura Akira
Kugai Kenichi
Noto Nobuhiro
Sato Takashi
Takahagi Hiroshi
Do An H.
Hitachi Printing Solutions, Ltd.
Meier Stephen D.
Whitham Curtis & Christofferson, P.C.
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