Metal working – Piezoelectric device making
Reexamination Certificate
2002-09-18
2003-08-26
Barlow, John (Department: 2853)
Metal working
Piezoelectric device making
C029S890100
Reexamination Certificate
active
06609280
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording head to be suitably used for a printer or a plotter.
A related ink jet recording head comprises a vibrator unit bonding a piezoelectric vibrator group to the surface of a fixation base formed of stainless steel, a casing for accommodating the vibrator unit, and a channel unit bonded to the tip portion of the casing and provided with a pressure chamber and a nozzle orifice.
The casing is molded of a synthetic resin, for example, and is provided with a housing space for accommodating and fixing the vibrator unit therein. The housing space is provided every vibrator unit. In a recording head comprising a plurality of vibrator units, therefore, a bulkhead portion molded integrally with the casing is provided between the adjacent housing spaces. The vibrator unit is bonded to the bulkhead portion and is thereby accommodated and fixed into the housing space.
For example, as shown in
FIG. 20
, the back face of a fixation base
1
is bonded to a bulkhead portion
2
so that a pair of vibrator units
3
are accommodated and fixed into housing spaces
4
. In such a fixing state, the tip end face of each of piezoelectric vibrators
5
is exposed to the outside of a casing
6
through an opening on the tip side of the housing space
4
, and the tip end face is bonded to an island portion
7
a
of an elastic plate
7
. The piezoelectric vibrator
5
is extended in the longitudinal direction of the vibrator depending on the supply of power to the piezoelectric vibrator
5
and the extension causes the elastic plate
7
to be deformed so that the volume of a pressure chamber
8
is changed. By the change in the volume of the pressure chamber
8
, therefore, a pressure fluctuation is generated on an ink in the pressure chamber
8
and an ink drop is discharged from a nozzle orifice
9
.
In the related recording head, thus, a plurality of housing spaces
4
are provided with the bulkhead portion
2
interposed therebetween and the vibrator unit
3
is accommodated and fixed every housing space
4
. For this reason, when the number of the vibrator units
3
to be accommodated and fixed into one recording head is increased, the size of the casing
6
is to be increased correspondingly so that the size of the recording head is increased.
Moreover, since the vibrator unit
3
is bonded to the bulkhead portion
2
, it is necessary to enhance the rigidity of the bulkhead portion
2
. In order to obtain a requisite rigidity, it is necessary to increase the thickness of the bulkhead portion
2
. Also in this respect, the size of the recording head is increased.
In a recent vibrator unit, particularly, the number of the piezoelectric vibrators provided in one vibrator unit tends to be increased. Therefore, a higher rigidity is required for the bulkhead portion. As a result, it is necessary to more increase the thickness of the bulkhead portion. Consequently, the size of the recording head is further increased.
Moreover, the casing
6
is generally formed of a synthetic resin. For this reason, in the case in which the recording head is put in a high humidity environment, the bulkhead portion
2
is swollen by moisture absorption as shown in FIG.
21
. By the swelling, the piezoelectric vibrators
5
might be inclined toward the outside. If the piezoelectric vibrator
5
is inclined, a stress is applied to a bonding interface of the piezoelectric vibrator
5
and the island portion
7
a
so that the piezoelectric vibrator
5
is easily peeled from the island portion
7
a
. Moreover, since an unnatural stress is applied to the elastic plate
7
, there is a possibility that a discharge characteristic might be adversely influenced.
SUMMARY OF THE INVENTION
The invention has been made in consideration of such circumstances and has a main object to provide an ink jet recording head which can be small-sized. Moreover, the invention has another object to provide an ink jet recording head capable of preventing drawbacks from being caused by the moisture absorption of a casing and ensuring workability and assembling properties and a method of manufacturing the ink jet recording head.
In order to achieve the above objects, according to the present invention, there is provided an ink jet recording head, comprising:
a channel forming substrate, in which a channel which extends from a common ink reservoir to nozzle orifices via pressure chambers associated with the respective nozzle orifices;
an elastic plate, a first surface thereof being bonded onto one surface of the channel forming substrate;
a supporting base formed with at least one through hole therein, a first face thereof being bonded onto a second surface of the elastic plate which is opposite to the first surface of the elastic plate;
a resin casing formed with an accommodation space therein, a first face thereof being bonded onto a second face of the supporting base which is opposite to the first face of the supporting base; and
at least one vibrator unit, including a fixation base, and piezoelectric vibrators arranged on a first face of the fixation base such that first ends of the piezoelectric vibrators are fixed thereon and opposite free ends overhang a second face of the fixation base, the vibrator unit accommodated in the accommodation space of the casing such that the piezoelectric vibrators extend through the through hole of the supporting base and the free ends thereof abut against the second surface of the elastic plate, and such that the second face of the fixation base is bonded onto the second face of the supporting base.
In this configuration, since the fixation base of the vibrator unit is bonded onto the supporting base, the size of the recording head can be reduced.
Moreover, it is possible to eliminate the bond of the casing and the vibrator unit, and to more decrease the bonding area than that in the related configuration. Therefore, it is possible to reduce a mechanical stress received by the vibrator unit due to the moisture absorption of the casing. Consequently, it is possible to eliminate a drawback caused by the mechanical stress, for example, to prevent a fluctuation in the discharge characteristic and the peeling of the piezoelectric vibrator from the elastic plate.
Preferably, the supporting base is made of metal material.
Here, it is preferable that the supporting base is made of stainless steel.
Preferably, the fixation base is made of metal material.
Here, it is preferable that the supporting base is made of metal material identical with the metal material forming the fixation base.
In the above configurations, the supporting base and the fixation base can be formed of a member having a relatively high rigidity. Therefore, the rigidity of the recording head can be increased and the reaction force applied from the piezoelectric vibrator can be received sufficiently. Consequently, the discharge characteristic of the ink drop can be stabilized. Furthermore, a member having high dimensional precision is used for the supporting base. Therefore, it is also possible to prevent a positional shift of the piezoelectric vibrator and the channel unit after the bonding.
Preferably, at least one concave groove is formed on the second face of the supporting base in the vicinity of the through hole, to hold adhesive for bonding the fixation base.
In this configuration, the adhesive can be selectively injected between the supporting base and the fixation base.
Here, it is preferable that there is defined a first gap between the second face of the supporting base and the second face of the fixation base, into which the adhesive held in the concave groove enters.
Further, it is preferable that a dimension of the first gap is so determined as to establish a capillary attraction therein.
In the above configurations, the adhesive can be reliably prevented from spilling. Furthermore, it is possible to position the vibrator unit with very high positional precision while reliably causing the piezoelectric vibrator to abut on the elastic plate.
Besides, it is preferab
Barlow John
Do An H.
Seiko Epson Corporation
Sughrue & Mion, PLLC
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