Metal working – Piezoelectric device making
Reexamination Certificate
2000-05-25
2002-10-01
Morris, Lesley D. (Department: 3754)
Metal working
Piezoelectric device making
C347S068000
Reexamination Certificate
active
06457222
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing an on-demand type multi-nozzle ink jet print head that is mounted in an ink jet printer for industrial and office uses.
2. Description of Related Art
There has been proposed a multi-nozzle ink jet print head that has a number of nozzles arranged with a high density and that employs a piezoelectrlc element to drive each nozzle.
SUMMARY OF THE INVENTION
In a conceivable ink jet print head of the piezoelectric type, a pressure chamber in provided to store ink therein. A diaphragm is provided as being exposed to the pressure chamber. A piezoelectric element is attached to the diaphragm. The piezoelectric element repeatedly expands and shrinks, whereby the diaphragm displaces repeatedly. The diaphragm generates a pressure variation in the pressure chamber, thereby allowing an ink droplet to be ejected from the pressure chamber through its orifice.
It is easy to control the displacement of the diaphragm and to change the amount of ink ejected. However, the piezoelectric element can displace the diaphragm only by a small amount in response to a unit amount of electric voltage. It is therefore necessary to make large the surface area of the diaphragm exposed in the pressure chamber. It is impossible to decrease the nozzle pitch to as small a 140 &mgr;m. Because the driving frequency depends on the shape of the piezoelectric element, the driving frequency can be increased to 20 kHz or more. The ink jet print head of the piezoelectric type can therefore enhance printing speed.
The conceivable ink jet print head of the piezoelectric type will be described below in greater detail with reference to FIG.
1
.
The conceivable multi-nozzle ink-jet print head
200
includes a plurality of nozzle rows which are arranged in a predetermined direction X. In each nozzle row, a plurality of nozzles are arranged in a predetermined direction Y which is perpendicular to the direction X. For each nozzle, the ink-jet print head has a pressure chamber
202
that stores ink and that has an orifice
201
to eject ink droplets onto an image recording medium, such as a sheet of paper (not shown), which is positioned confronting the orifice
201
. The ink-jet print head
200
has a manifold
208
, in correspondence with each nozzle row, for supplying ink to all the pressure chambers
202
that reside in the nozzle row. Each manifold
208
extends in the predetermined direction Y. Each pressure chamber
202
is in fluid communication, via a corresponding restrictor channel
207
, to the corresponding manifold
208
. The ink-jet print head
200
has a plurality of piezoelectric elements
204
in one to one correspondence with the plurality of pressure chambers
202
. A single diaphragm
203
is connected, via elastic material (silicone adhesive material, for example)
209
, to the top surfaces
218
of all the plurality of piezoelectric elements
204
. The diaphragm
203
is exposed to each pressure chamber
202
in its surface that is opposed to the surface, where the diaphragm
203
is attached to the top surface
218
of the corresponding piezoelectric element
204
.
More specifically, the ink-jet print head
200
has a single base plate (piezoelectric element-fixing plate)
206
. The plurality of piezoelectric elements
204
are fixedly mounted on the base plate
206
. The piezoelectric elements
204
are arranged in the plurality of nozzle rows. The plurality of nozzle rows are arranged in the predetermined direction X, with each nozzle row extending in the predetermined direction Y. Each piezoelectric element
204
has a pair of external electrodes
214
a
and
214
b
at their side surfaces
220
a
and
220
b.
A manifold-forming assembly
280
is provided over the piezoelectric elements
204
to provide the manifolds
208
.
A single support plate
213
is mounted over both the manifold-forming assembly
280
and the piezoelectric elements
204
in order to reinforce the diaphragm
203
. The support plate
213
is formed with a plurality of openings
217
a
in one to one correspondence with the plurality of piezoelectric elements
204
. The diaphragm
203
is mounted over the support plate
213
. The diaphragm
203
has a plurality of oscillating areas
230
that are exposed through the corresponding openings
217
a
to confront the top surfaces
218
of the plurality of piezoelectric elements
204
. Substantially the central portions of the oscillating areas
230
are connected via elastic material
209
to the top surfaces
218
of the piezoelectric elements
204
.
A restrictor plate
210
is mounted over the diaphragm
203
to provide a restrictor channel
207
for each piezoelectric element
204
. A pressure chamber plate
211
is mounted over the restrictor plate
210
to provide a pressure chamber
202
for each piezoelectric element
204
. A nozzle plate
212
is mounted over the chamber plate
211
to provide an orifice
201
to each pressure chamber
202
.
With the above-described structure, electric signals are repeatedly applied to the external electrodes
214
a
and
214
b
of each piezoelectric element
204
via input signal terminals
205
a
and
205
b.
As a result, electric potentials repeatedly occur between the external electrodes
214
a
and
214
b,
and the piezoelectric element
204
repeatedly expands and shrinks in a direction substantially normal to the surface of the base plate
206
. The oscillating area
230
of the diaphragm
203
, that is connected to the top surface
218
of the piezoelectric element
4
, oscillates in directions near to and away from the orifice
201
, thereby producing pressure variations in the pressure chamber
202
. Ink droplets are ejected from the pressure chamber
202
via the orifice
201
. Thus, the piezoelectric element
204
and the corresponding oscillating area
230
in the diaphragm
203
cooperate to serve as an oscillating system.
It is conceivable that the ink-jet print head
200
halving the above-described structure be manufactured in a manner described below.
A plurality of bar- or rod-shaped original piezoelectric elements (which will be referred to as “piezoelectric element bars”, hereinafter) are first prepared. The number of the piezoelectric element bars is equal to the total number of nozzle rows to be mounted in the print head
200
. Each piezoelectric element bar has a top surface
218
and toe pair of slia surfaces
220
a
and
220
b
which are provided with the pair of external electrodes
214
a
and
214
b,
respectively. Each piezoelectric element bar is cut at their two corners
215
a
and
215
b
which are defined between the top surface
218
and the side surfaces
220
a
and
220
b.
This corner-cutting operation is required to prevent the external electrodes
214
a
and
214
b
from being short-circuited to the diaphragm
203
when the diaphragm
203
is bonded to the top surface
218
and also to ensure sufficient amounts of margin in relative positions between the oscillating areas
230
of the diaphragm
203
and the top surfaces
208
of the piezoelectric elements
204
. For example, a grinder is pressed against each corner
215
a,
215
b
of each piezoelectric element
204
, thereby beveling the corner
215
a,
215
b.
After being subjected to the corner-cutting process, all the piezoelectric element bars are arranged on the base plate
206
in the predetermined direction X so that each piezoelectric element bar extends in the predetermined direction Y. Then, the piezoelectric element bars are bonded to the base plate
206
. Each piezoelectric element bar is then subjected to a dicing process, in which each piezoelectric element bar is cut into a plurality of individual piezoelectric elements
204
along the predetermined direction Y. This dicing process is performed using a dicing saw.
Thus, in the above-described conceivable production steps, each piezoeloctric element bar is first cut at their corners
215
a
and
215
b,
is attached to the base plate
206
, and then is finally diced into the plurality
Akiyama Yoshitaka
Kugai Kenichi
Kurosawa Nobuhiro
Noto Nobuhiro
Suematsu Shigenori
Hitachi Koki Co,. Ltd.
Keasel Eric
Morris Lesley D.
Whitham Curtis & Christofferson, PC
LandOfFree
Method of manufacturing ink jet print 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 Method of manufacturing ink jet print head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing ink jet print head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2921887