Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-06-23
2001-12-11
Fuller, Benjamin R. (Department: 2855)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S064000
Reexamination Certificate
active
06328432
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to an ink jet recording head having grooves of ink flowing paths and a method of production thereof, more particularly, it relates to an ink jet recording head and a method of production thereof which are applied to a printer, and a duplicating machine, etc.
2. Description of the Related Art:
A conventional ink jet recording head is described in Japanese Laid-Open Patent Publication No. 6-246913 published on Sep. 6, 1994. Referring to
FIG. 5
, the conventional ink jet recording head is explained. This figure is a cross sectional view illustrating the structure of the conventional ink jet recording head. The head as illustrated in the figure has a structure in which a piezo-electric ceramic element
11
provided with a plurality of grooves
22
and subjected to a polarization treatment in the direction of an arrow
14
is bonded, through a bonding layer
13
of an epoxy based adhesive, to a cover plate
12
of a ceramic material or a resinous material and so on. According to the above constitution, a plurality of the grooves
22
are formed for serving as ink flowing paths. Each ink flowing path is long and narrow in shape and oblong in a cross section, and a side wall
21
is extended over a whole length of the ink flowing path.
An metal electrode
23
for generating a driving electric field is formed on both of the side surfaces of the side wall
21
, ranging from the upper portion of the side wall
21
near the adhesion layer
13
on the top of the side wall
21
to the middle portion thereof. Also, a protective layer
30
is formed for covering the electrode
23
. Every ink flowing path is filled with ink.
Next, a method of producing the conventional head will be explained. First, the piezo-electric ceramic element
11
is provided with a groove
22
by a cutting work utilizing a thin disk-shaped diamond blade. The metal electrode
23
is formed on an inner side wall of the groove by a sputtering method and so on. Further, the protective film
30
is so made on the inner wall of the groove
22
as to cover the electrode
23
.
In a ink jet recording head having such a structure, at the time of being driven, the metal electrodes
23
d
and
23
g
are ground and a positive voltage is applied to the metal electrodes
23
e
and
23
f
. Then, the direction of an electric field generated by the application of the voltage and the direction of a polarization thereby in each of the side walls
21
b
and
21
c
are positioned rectangularly with each other. Accordingly, the side walls
21
b
and
21
c
are deformed each toward the inside of the groove
22
b
through a piezo-electric thickness slide effect. As a result, the ink within the groove
22
b
is pressurized so that the ink is jetted from a nozzle not shown in any figures.
There are the following problems in an ink jet recording head having such a structure that some grooves are formed on a piezo-electric element by a cutting work and the resulting side walls of the grooves are driven to thereby jet each ink in the grooves.
That is to say, the strength of the side wall is weak because fine cracks are produced in the outer surface of the side wall of the groove by a cutting work, and the cracks are developed further to ends in destroying the side wall or causing the like while the side wall is driven for a long time, which brings a problem in reliability. On the other hand, if a width of the side wall is enlarged in order to reduce the bad influence attributable to the cracks, an interval between the grooves becomes so large as not to allow the nozzles connected the grooves to be disposed in high density.
In another aspect, there is a large surface roughness in the side wall surface which is a surface obtained by subjecting a piezo-electric ceramic substrate to a cutting work. Therefore, the convex portions in the side wall surface are coated with the electrode material and the protective film, however, the concave portions therein have the difficulty to be coated therewith. If the electrode does not contact sufficiently with a piezo-electric ceramic substrate, it decreases an amount of deformation of the side wall. In the case that a coating of the protective film is insufficient, an insulation resistance of the protective film is so lowered as to bring about such defects as an electric current leak into ink and a corrosion of the electrode.
The invention is made to overcome the above disadvantages of the prior art, the object of the present invention is to provide an ink jet recording head in which the strength of the side wall is high and a surface roughness of the side wall is small, and a method of producing the same.
SUMMARY OF THE INVENTION
An ink jet recording head of the present invention is such an ink jet recording head wherein a voltage is applied to an electrode formed on the side wall of a groove provided in a piezo-electric ceramic substrate to thereby jet the ink filled into the groove, and it comprises, as a feature, a mending film interposed on the side wall for mending the irregularities of the side wall.
A method of producing an ink jet recording head according to the present invention is such a method as to produce an ink jet recording head wherein a voltage is applied to an electrode formed on the side wall of a groove provided in a piezo-electric ceramic substrate to thereby jet the ink filled into the groove, and the method comprises, as a feature, a groove formation step of providing a groove in the piezo-electric ceramic substrate and a mending film formation step of providing a mending film on the side wall surface for mending the irregularities thereof.
The mending film has such a feature that it is of an oxide material. The oxide material is characterized in that it is of a lead-zirconium-titanium based oxide, for example.
In short, according to the present invention, there is formed on the side wall surface of the groove a mending film for mending the irregularities which appears on the side wall surface when the grooves are formed for an ink jet recording head. By providing the mending film, the strength of the side wall is largely improved and the cover ability of each of the electrode and the protective film is also made better. The improved coverability of each of the electrode and the protective film prevents a leak of current to thereby raise the reliability.
REFERENCES:
patent: 5677717 (1997-10-01), Ohashi
patent: 5719606 (1998-02-01), Kigawa et al.
patent: 0 612 619 A1 (1994-08-01), None
patent: 0 768 181 A1 (1997-04-01), None
patent: Sho 63-65686 (1988-03-01), None
patent: Hei 4-206870 (1992-07-01), None
patent: Hei 4-263955 (1992-09-01), None
patent: Hei 6-20866 (1994-01-01), None
patent: 6-246913 (1994-09-01), None
patent: 10-93153 (1998-04-01), None
patent: 10-119264 (1998-05-01), None
Kiyomitsu, S., “Manufacture of Ink Jet Head,”Patent Abstracts of Japan, Oct. 31, 1997.
Yumiko, O., “Ink Jet Printer Head,”Patent Abstracts of Japan, Nov. 15, 1994.
English translation of Japanese Office Action dated Mar. 16, 1999 (Hei 11).
Japanese Office Action, dated Nov. 17, 1998, with English language translation of Japanese Examiner's comments.
Dickens C.
Fuller Benjamin R.
NEC Corporation
Whitham, Curtis & Christofferson
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