Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-03
2003-10-14
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06631981
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric actuator in the form of a plate used in a piezoelectric ink jet printer head, and more specifically to configuration of common electrodes and individual electrodes of such a piezoelectric actuator.
2. Description of Related Art
FIG. 1
shows a conventional piezoelectric ink jet printer head
100
disclosed in U.S. Pat. No. 5,402,159. As shown in
FIG. 1
, the conventional head
100
includes a nozzle plate
117
, a cavity plate
115
, a piezoelectric actuator
111
in the form of a plate, and a back plate
119
. The nozzle plate
117
is formed with a plurality of nozzles
118
. The cavity plate
115
is formed with a plurality of ink cavities
116
, each corresponding to one of the plurality of nozzles
118
.
The piezoelectric actuator
111
includes a plurality of piezoelectric ceramic layers
110
called green sheets. Individual electrodes
112
are formed on each of a half of the piezoelectric ceramic layers
110
, and a common electrode
113
is formed on each of another half of the piezoelectric ceramic layers
110
. These two types of layers are alternatively arranged one on the other to have a laminated structure. Each of the individual electrodes
112
corresponds to one of the ink cavities
116
. The common electrodes
113
are common to all the ink cavities
116
.
The piezoelectric actuator
111
also includes outer electrodes
114
formed on its side surface by vacuum metallizing, metal spattering, conductive paste coating, or the like. Each outer electrode
114
electrically connects one of the sets of the individual electrodes
112
to the outside.
However, in this configuration, when the end portion of each individual electrode
112
may not reach the side surface of the piezoelectric actuator
111
, the electrical connection between the individual electrode
112
and the outer electrode
114
would be insufficient. Also, during the conductive paste coating and the like for forming the outer electrode
114
, the orientation of the piezoelectric actuator
111
is changed such that its side surface faces upward. This complicates the production process.
Moreover, there is a danger that the electrical connection of the electrodes
112
and
114
is damaged by accidentally contacting a handler or a tool during the production or assembly of the piezoelectric actuator
111
.
In order to overcome these problems, as shown in
FIGS. 2 through 4
, Japanese Patent Publication No. HEI-7-96301 has proposed to form a lead-out electrode
8
a
,
9
a
to each of the individual and common electrodes
8
,
9
. A plurality of first through-holes
2
are formed to penetrate through piezoelectric ceramic sheets
6
and the lead-out electrodes
8
a
of the corresponding individual electrodes
8
. Also, a second through hole
3
is formed to penetrate through piezoelectric ceramic sheets
6
and the lead-out electrodes
9
a
of the common electrodes
9
. Then, each of the first and second through holes
2
,
3
are filled with conductive paste, so that the individual electrodes
8
and the common electrodes
9
are electrically connected to an external electrode through the through holes
2
and
3
.
In this case, the through holes
2
,
3
are formed to all the piezoelectric ceramic sheets
6
, but not to a cavity plate
4
, which is formed with ink cavities
4
a
and an ink channel
4
b
. However, because the cavity plate
4
is formed from a piezoelectric ceramic sheet also, when the through holes
2
,
3
are formed connected to the ink cavities
4
a
or the ink channel
4
b
, short circuits will result. Therefore, in order to avoid the short circuit, positions of the through holes
2
,
3
need to be carefully selected, and so the configuration of a piezoelectric actuator is strictly restricted.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to overcome the above problems, and also to provide a piezoelectric actuator with a configuration enabling simplifying a production process while avoiding short circuits and warping.
In order to achieve the above and other objectives, there is provided an ink jet print head including a cavity plate and a piezoelectric actuator. The cavity plate is formed with a plurality of nozzles and a plurality of pressure chambers each corresponding to one of the plurality of nozzles. The piezoelectric actuator includes a plurality of first piezoelectric sheets extending in a first direction, a plurality of second piezoelectric sheets extending in the first direction, a plurality of individual electrodes each corresponding to one of the plurality of pressure chambers and formed on the surface of the first piezoelectric sheets, and a plurality of common electrodes common to the plurality of pressure chambers and formed on the surface of the second piezoelectric sheets. The first piezoelectric sheets and the second piezoelectric sheets are arranged one on the other in alternation in a second direction perpendicular to the first direction so as to form a laminated structure. One of the first and second piezoelectric sheets at an end of the laminated structure lies on the cavity plate. The piezoelectric actuator is formed with first through holes formed in each of the first and second piezoelectric sheets in the second direction, except the one of the first and second piezoelectric sheets lying on the cavity plate. Each of the plurality of individual electrodes is formed at a position corresponding to the first through holes on the first piezoelectric sheets. The first through holes is filled with conductive material, thereby electrically connecting corresponding ones of the plurality of individual electrodes.
There is also provided a piezoelectric actuator used in a recording head including a cavity plate formed with a plurality of nozzles aligned in a first direction, and a plurality of channels each corresponding to one of the plurality of nozzles. The piezoelectric actuator includes a plurality of first piezoelectric sheets having a surface, a plurality of second piezoelectric sheets having a surface, and a plurality of first electrode patterns. The plurality of first piezoelectric sheets and the plurality of second piezoelectric sheets are arranged one on the other in a thickness direction perpendicular to the first direction. Each of the first electrode patterns is formed on the surface of one of the plurality of first piezoelectric sheets, and formed with a gap having a width in a second direction perpendicular to both the first direction and the thickness direction. The gaps of ones of the first electrode patterns are positioned shifted in the second direction from the gaps of another ones of the first electrode patterns.
REFERENCES:
patent: 4805057 (1989-02-01), Ogawa et al.
patent: 5402159 (1995-03-01), Takahashi et al.
patent: 7-96301 (1995-10-01), None
patent: 09150517 (1997-06-01), None
patent: 09162450 (1997-06-01), None
patent: 11233847 (1999-08-01), None
Isono Jun
Takagi Atsuhiro
Brother Kogyo Kabushiki Kaisha
Oliff & Berridg,e PLC
Vo Anh T. N.
LandOfFree
Piezoelectric actuator of ink jet printer head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Piezoelectric actuator of ink jet printer head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Piezoelectric actuator of ink jet printer head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3152100