Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2003-03-06
2004-12-14
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06830319
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a head chip to be mounted on an ink-jet recording apparatus applicable, for example, to a printer, a facsimile apparatus, or an on-demand printer, and to a method of producing the head chip.
2. Description of the Related Art
An ink-jet recording apparatus has been known which records characters and images on a recording medium by using an ink-jet head on which there is mounted a head chip having a plurality of nozzles for ejecting ink.
Examples of the conventional ink-jet recording apparatus include a serial type ink-jet recording apparatus in which the nozzles of the head chip are arranged in the ink-jet head so as to be opposed to the recording medium and in which scanning is effected with the ink-jet head in a direction perpendicular to the transporting direction of the recording medium to thereby perform printing, and a line type ink-jet recording apparatus in which the ink-jet head is stationary, printing being effected by moving the recording medium alone.
Examples of the head chip to be mounted on a conventional ink-jet head are disclosed, for example, in JP2000-512233A and JP2000-296618 A (See Patent Documents 1 and 2).
FIGS. 10A and 10B
are sectional views showing the conventional head chip as disclosed in the former document.
As shown in
FIG. 10A
, a head chip
100
comprises: a substrate
120
composed of a substrate main body
121
formed of an insulating material such as alumina and having in one surface thereof a recess, and piezoelectric ceramic members
122
provided in the recess and having a plurality of grooves
125
extending in a direction perpendicular to the longitudinal direction thereof; and a nozzle plate
140
joined to the substrate
120
so as to cover the open side of the recess and having nozzle openings
141
.
Formed in the substrate main body
121
are chambers
130
defined by the piezoelectric ceramic members
122
at either end of the recess in the width direction so as to extend in the longitudinal direction.
Further, electrodes
127
are formed on side walls
126
defining the grooves
125
of the piezoelectric ceramic
122
, and each electrode
127
is electrically connected to a lead wiring provided on the recess side surface of the nozzle plate
140
.
Further, in the bottom surface of the substrate main body
121
, there are provided an ink supply hole
131
and an ink discharge hole
132
for supplying and discharging ink to and from each chamber
130
.
In this head chip
100
, ink is supplied from one chamber
130
, and supplied to the other chamber
130
through the grooves
125
of the piezoelectric ceramic
122
, whereby ink is supplied to the interior of the grooves
125
.
And, by applying voltage to the electrodes
127
provided on the side walls
126
, the side walls
126
undergo shear mode displacement, whereby the ink filling the grooves
125
is ejected through the nozzle openings
141
.
To perform high speed printing with this head chip
100
with the number of nozzle openings
141
increased, piezoelectric ceramic members
122
with the plurality of grooves
125
are provided side by side in the recess of the substrate main body
121
, and the nozzle openings
141
are provided in the areas opposed to the grooves
125
, as shown in
FIG. 10B
, whereby the number of nozzle openings
141
in the head chip
100
is doubled.
In producing this head chip
100
, the recess is formed in the substrate main body
122
, and the piezoelectric ceramic members
122
with the plurality of grooves
125
are positioned and secured to predetermined positions on the bottom surface of the recess to form the substrate
120
, and then the nozzle plate
140
is joined to the substrate to complete the head chip
100
.
FIG. 11
shows a head chip as disclosed in the latter document.
FIG. 11
is a cut-away perspective view of a main portion of the conventional head chip.
As shown in the drawing, a head chip
200
includes a substrate
220
consisting of a substrate main body
221
formed of an insulating material such as alumina and equipped with a recess
224
open at one end surface and one surface, and piezoelectric ceramic members
222
embedded in the recess
224
, wherein a plurality of grooves
225
are defined by side walls
226
so as to extend over the substrate main body
221
and the piezoelectric ceramic members
222
and in the longitudinal direction of the recess
224
.
One end portion of each of the grooves
225
formed in the substrate
220
is open at one end surface of the piezoelectric ceramic members
222
, and the other end portions thereof extend up to the substrate main body
221
with their depth gradually decreasing.
Further, electrodes (not shown) are provided on the side walls
226
defining the grooves
225
of the piezoelectric ceramic
222
, and the electrodes are electrically connected to lead wiring
227
a
provided in the region of the substrate main body
221
where no grooves
225
are formed.
Further, a nozzle plate
240
having nozzle openings
241
at regions opposed to the grooves
225
is joined to one end surface of the substrate
220
where the grooves
225
are open, and on one side of the substrate
220
where the grooves
225
are open, there is provided an ink chamber
230
communicating with the grooves
225
and adapted to supply ink to the grooves
225
. Further, joined to this side of the substrate is an ink chamber plate
231
for sealing the region of the grooves
225
which does not face the ink chamber
230
.
In producing this head chip
200
, the recess
224
is formed in the substrate main body
221
, and the piezoelectric ceramic
222
is embedded in the recess
224
to thereby form the substrate
220
, the grooves
225
being formed by simultaneously grinding the substrate main body
221
and the piezoelectric ceramic
222
with a dicer using a disc-shaped dice cutter. And, the electrodes are formed-on the side walls
226
defining the grooves
225
, and the lead wiring
227
a
is formed in the substrate main body
221
, the nozzle plate
240
and the ink chamber plate
231
being joined to the substrate to form the head chip
200
.
In this head chip
200
, the piezoelectric ceramic
222
is embedded in the substrate main body
221
, and then the plurality of grooves
225
are formed, so that it is possible to reduce product defects and to achieve an improvement in yield.
In the former type of head chip, however, it is necessary to perform positioning on the piezoelectric ceramic members when fixing them to predetermined positions on the bottom surface of the recess of the substrate main body, and high precision positioning is rather difficult to perform.
Further, in the former type of head chip, when forming grooves in the piezoelectric ceramic members, the side walls defining the grooves are subject to breakage, resulting in poor yield.
In the former type of head chip, the number of nozzle openings can be doubled by arranging the piezoelectric ceramic members side by side in the recess, so that it allows high speed printing in a serial type ink-jet recording apparatus, in which the ink-jet head with the head chip mounted thereon is moved in a direction perpendicular to the transporting direction of the recording medium, whereas, in a line type ink-jet recording apparatus, in which the recording medium is moved with the ink-jet head being stationary, the nozzle opening positions in the row direction are the same in each row of nozzle openings, so that it is impossible to perform high density printing.
On the other hand, in the latter type of head chip, when the number of nozzle openings are to be increased in order to perform high speed printing or high density printing, the head chips have to be arranged side by side, which leads to an increase in head chip size and an increase in cost.
Further, when a conductive ink such as a water-color ink is used in the head chips of both types, adjacent electrodes provided on side walls defining a groove conduct to eliminate the potential difference, with the re
Harajiri Toshihiko
Hongou Yutaka
Adams & Wilks
Nguyen Thinh
SII Printek Inc.
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