Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-04-19
2003-04-15
Nguyen, Judy (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S071000
Reexamination Certificate
active
06547376
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ink jet head, and to a method for the manufacture thereof.
BACKGROUND OF THE INVENTION
Ink jet recording devices making utilization of the piezoelectric effect of piezoelectric elements to effect printing have been used as a printer, a word processing machine, a facsimile machine, etc. Some ink jet recording devices employ an ink jet head having a multi-level layered construction of thin films, like the one shown in
FIGS. 14 and 15
.
Referring to the ink jet head-of the figures, formed in the interior of a main body portion
108
of the head are a plurality of pressure chambers
101
which are arranged along a direction L
2
, and a common ink chamber
102
which has a long and narrow shape in the direction L
2
. Each of the plurality of pressure chambers
101
is formed into a strip-like shape having a horizontal cross section which has a long and narrow shape in a direction L
1
. The pressure chambers
101
are in communication through their respective ink supply passages
105
with the common ink chamber
102
. Nozzle orifices
103
are formed in a front side of the ink jet head (the lower one of the sides of the ink jet head in FIG.
14
). The nozzle orifice
103
is in communication through an ink discharging passage
104
with the pressure chamber
101
. Each pressure chamber
101
is compartmented with an oscillation plate
112
at its back side (the upper one of the sides in FIG.
14
). The oscillation plate
112
is formed of Cr (chromium) and functions as a common electrode for applying a voltage to piezoelectric elements
106
. The piezoelectric element
106
is jointed to a back side of the oscillation plate
112
. Mounted on a back side of the piezoelectric element
106
is an individual electrode
111
. The individual electrode
111
, the piezoelectric element
106
and the oscillation plate
112
together form an actuator portion
107
for applying a pressure to the ink in the pressure chamber
101
. The main body portion
108
and the oscillation plate
112
are bonded together by an adhesive
120
.
With the recent advancement of the resolution of recording devices to a higher degree, the miniaturization of head structures has been improved. Correspondingly, the gap between two piezoelectric elements
106
next to each other becomes shorter as shown in FIG.
15
and the thickness of a compartmenting wall
109
which compartments the pressure chamber
101
becomes thinner. Accordingly, when adhering together the main body portion
108
and the oscillation plate
112
, there are some cases in which the adhesive
120
is forced out of the butt surface, as indicated by the virtual line (the two-dot chain line) of
FIG. 15 and a
part
114
of the forced-out adhesive adheres to a displacement portion
113
of the oscillation plate
112
. This causes the displacement portion
113
of the oscillation plate
112
to decrease in its displacement amount, in addition to which the displacement portion
113
is stopped from performing a smooth displacement operation, therefore resulting in a drop in the ink discharging performance. Further, it is possible that the displacement amount of the oscillation plate
112
varies from one pressure chamber to another, resulting in poor print quality.
Bearing in mind the above-described problems with the prior art techniques, the invention was made. Accordingly, an object of the present invention is to provide such adhesion between a head main body and an oscillation plate that the adhesive will not become an obstacle to the displacement operation of the oscillation plate.
SUMMARY OF THE INVENTION
In order to achieve the object, the present invention provides an ink jet head. More specifically, the ink jet head of the present invention comprises (a) a head main body portion in which a pressure-chamber recess portion and a nozzle orifice are formed and (b) an actuator portion having (i) an oscillation plate which covers the pressure-chamber recess portion of the head main body portion so as to form, together with the head main body portion, a pressure chamber in the form of a compartment and (ii) a piezoelectric element which is rigidly fixed to the oscillation plate whereby the displacement of the oscillation plate generated by the piezoelectric effect of the piezoelectric element forces ink in the pressure chamber out of the nozzle orifice, wherein an intermediate layer is formed between the oscillation plate and the head main body portion for the prevention of adhesive adhesion to the oscillation plate and wherein the oscillation plate and the head main body portion are rigidly fixed together by an adhesive through the intermediate layer.
As a result of such arrangement, even when a part of the adhesive is forced out in adhering together the head main body and the oscillation plate, the provision of the intermediate layer between the adhesive and the oscillation plate causes the forced-out adhesive to adhere to the intermediate layer. Accordingly, the forced-out adhesive is prevented from adhering to the displacement portion of the oscillation plate, therefore ensuring that the oscillation plate satisfactorily performs its displacement operation. As a result, the variation in displacement is prevented, thereby achieving a stable ink discharging performance.
The present invention provides another ink jet head which comprises (a) a head main body portion in which a pressure-chamber recess portion and a nozzle orifice are formed and (b) an actuator portion having (i) an oscillation plate which covers the pressure-chamber recess portion of the head main body portion so as to form, together with the head main body portion, a pressure chamber in the form of a compartment and (ii) a piezoelectric element which is rigidly fixed to the oscillation plate whereby the displacement of the oscillation plate generated by the piezoelectric effect of the piezoelectric element forces ink in the pressure chamber out of the nozzle orifice, wherein an intermediate layer having a window portion through which a displacement portion of the oscillation plate is exposed to the pressure chamber, and consisting of metal, ceramics, or resin is formed on a surface of the oscillation plate on the side of the head main body, and wherein the oscillation plate and the head main body portion are rigidly fixed together by an adhesive through the intermediate layer.
Accordingly, by the use of thin film formation technology including sputtering and CVD, the intermediate layer used for the prevention of adhesive adhesion to the displacement portion of the oscillation plate can be formed easily.
The use of copper facilitates the formation of relatively thick films, and therefore the intermediate layer is preferably formed of copper. As a result of such arrangement, it is possible to easily form the intermediate layer having a thicker film thickness capable of the prevention of adhesive adhesion to the oscillation plate without fail. Moreover, the copper is superior in workability, that is, it is easily etched. Therefore, the window portion can be formed easily.
The intermediate layer may be formed of titanium. This extends the life span of the intermediate layer because the titanium is not readily degraded even when exposed to the ink. Moreover, the degree of adhesion between titanium and chromium is high, so that, when chromium is used for the oscillation plate, the adhesion with respect to the oscillation plate is enhanced. Accordingly, there is no need for the provision of an adhesion improving layer used to improve the degree of adhesion between the intermediate layer and the oscillation plate, whereby the manufacture process can be shortened.
If the intermediate layer is formed too thin, then the adhesive is likely to adhere to the displacement portion of the oscillation plate. Taking into account this point, it is preferred that the intermediate layer is formed, having a thickness of 5 &mgr;m or greater. As a result of such arrangement, it becomes possible to effectively prevent the adhesive from adhering t
Kanno Isaku
Matsuo Koji
Tanaka Eiichiro
Tomita Kenji
Watanabe Osamu
Harness Dickey & Pierce PLC
Nguyen Judy
Tran Ly T
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