Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-05-24
2003-05-27
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06568796
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a head chip that is mounted on an ink-jet type recording apparatus applicable to, for example, a printer and a facsimile, and a head unit using the head chip.
2. Description of the Related Art
Conventionally, an ink-jet type recording apparatus is known in the technical field, in which a recording head for jetting ink droplets from a plurality of nozzles is employed to record characters and/or images on a recording medium. In such an ink-jet type recording apparatus, the recording head positioned opposite to the recording medium is provided on a head holder, and the head holder is mounted on a carriage so as to be scanned along a direction perpendicular to a transport direction of the recording medium.
In
FIG. 14
, there is shown an exploded/perspective view of one example of such a recording head.
FIGS. 15A and 15B
are sectional view of a major portion of this recording head.
FIG. 15A
is a sectional view of the recording head taken along the longitudinal direction of side walls.
FIG. 15B
is a sectional view of the recording head taken along the thickness direction of side walls. As shown in FIG.
14
and
FIG. 15
, a plurality of grooves
102
are arranged in a piezoelectric ceramic plate
101
in a parallel manner. The respective grooves
102
are separated from each other by side walls
103
. One end portion of each of the grooves
102
in the longitudinal direction is elongated up to one end surface of the piezoelectric ceramic plate
101
, whereas the other end portion is not elongated up to the other end surface of this piezoelectric ceramic plate, and a depth thereof gradually becomes shallow. Also, an electrode
105
for applying a driving electric field is formed on surfaces of both the side walls
103
on the opening side within each of the grooves
102
along the longitudinal direction.
A cover plate
107
is jointed via an adhesive agent
109
to the grooves
102
of the piezoelectric ceramic plate
101
on the opening side. This cover plate
107
has an ink chamber
111
that constitutes a concave portion which is communicated to the shallow other end portion of each of the grooves
102
and an ink supply port
112
that is penetrated through a bottom portion of this ink chamber
111
along a direction opposite to the direction of the grooves
102
.
A nozzle plate
115
is joined to an end surface of a joint member made by the piezoelectric ceramic plate
101
and the cover plate
107
, at which the grooves
102
are opened. Nozzle openings
117
are formed in the nozzle plate
115
at such positions located opposite to the respective grooves
102
.
It should be noted that a wiring board
120
is fixed on such a surface of the piezoelectric ceramic plate
101
, which is located opposite to the nozzle plate
115
and also opposite to the cover plate
107
. A wiring line
122
which is electrically connected to each of the electrodes
105
by employing a bonding wire
121
or the like is formed on the wiring board
120
. A driver voltage may be applied via this wiring line
122
to the electrode
105
.
In the,recording head constituted as described above, when ink is filled from the ink supply port
112
into the respective grooves
102
and a predetermined driving electric field is applied via the electrode
105
to the side walls
103
on both sides of a predetermined groove
102
, the side walls
103
are deformed, so that a capacity formed within this predetermined groove
102
is changed. As a result, the ink filled in the grooves
102
may be jetted from the nozzle opening
117
.
For example, as shown in
FIG. 16
, in the case where ink is jetted from a nozzle opening
117
corresponding to a groove
102
a
, a positive driving voltage is applied to both electrodes
105
a
and
105
b
provided in the groove
102
a
, and also electrodes
105
c
and
105
d
located opposite to these electrodes
105
a
and
105
b
are grounded. As a consequence, a driving electric field directed to the groove
102
a
is effected to the side walls
103
a
and
103
b
. When this driving electric field is positioned perpendicular to the polarization direction of the piezoelectric ceramic plate
101
, both the side walls
103
a
and
103
b
are deformed along the direction of the groove
102
a
due to the piezoelectric thickness slip effect, so that the capacity defined in the groove
102
a
is reduced to thereby increase pressure. Thus, the ink may be jetted from the nozzle opening
117
.
Further, such a head chip is mounted on an ink jet type recording apparatus, and this has widely spread as a color printer by using color ink. Along with this, it is required that printing quality and recording density are improved.
However, in the case where grooves are arranged with high density for improving the printing quality and the recording density, there is a problem in that the thickness of the side walls between the respective grooves becomes thinner, and thus rigidity of the side walls is insufficient, thereby causing generation of crosstalk between respective chambers.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above, and an object of the present invention is to provide a head chip and a head unit in which recording density is improved and also manufacturing cost is reduced.
In order to solve the above problems, according to a first aspect of the present invention there is a head chip in which: partition walls made of piezoelectric ceramic are arranged on a board with predetermined intervals; chambers are defined between the respective partition walls; a driver voltage is applied to electrodes provided on the side surfaces of the partition walls to change the capacity in the chambers; and the ink filled in the chambers is jetted from nozzle openings, characterized in that the chambers are arranged between upper and lower sheets of boards, which are made of a dielectric material having a light transmitting property, in the width direction with predetermined intervals, and also a plurality of the boards are laminated in the vertical direction.
According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a head chipcharacterized in that a plurality of units, in which the partition walls are arranged between two boards with predetermined intervals, are laminated.
According to a third aspect of the present invention, in the first aspect of the present invention, there is provided a head chip characterized in that the partition walls are arranged on both surfaces of a board with predetermined intervals.
According to a fourth aspect of the present invention, in the first aspect of the present invention, there is provided a head chip, characterized in that:
a nozzle plate having the nozzle openings that communicate with the chambers is provided at end surfaces of the partition walls in the longitudinal direction; and
ink chambers that communicate with the respective chambers, are provided on the side of the other end portions of the partition walls.
According to a fifth aspect of the present invention, in the fourth aspect of the present invention, there is provided a head chip characterized in that the nozzle plate is formed of a dielectric material.
According to a sixth aspect of the present invention, there is provided a head unit characterized in that the head unit comprises a head chip as described above and a head holder that mounts the head chip.
According to a seventh aspect of the present invention, in the sixth aspect of the present invention, there is provided a head unit characterized in that the head holder may detachably hold an ink cartridge in which ink is stored.
According to the present invention, alignment of chambers when arranging in parallel the chambers on both surfaces of the board can be easily performed by using the board formed from a transparent dielectric material, and thus recording density can be improved.
REFERENCES:
patent: 5557309 (1996-09-01), Hayes
patent: 5619235 (1997-04-
Adams & Wilks
Nguyen Thinh
Seiko Instruments Inc.
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