JP3456518B2 - Piezoelectric vibrator unit and ink jet recording head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator unit suitable for expanding and contracting a pressure generating chamber of an ink jet recording head , and this piezoelectric vibrator unit.
The inkjet recording head used .

[0002]

2. Description of the Related Art An ink jet recording head using a longitudinal vibration mode piezoelectric vibrator has a narrow gap on the back surface of a nozzle plate having a plurality of nozzles as disclosed in Japanese Patent Laid-Open No. 1052/1992. And an elastic plate is disposed on the back surface of the elastic plate, and a piezoelectric vibrator having a piezoelectric constant d31 is divided into contact with the back surface of the elastic plate so as to correspond to each pressure generating chamber of the flow path forming substrate. After being guided to the pressure generating chamber via the supply port, the ink here is pressurized by a piezoelectric vibrator driven according to a recording signal and ejected as an ink droplet from a nozzle opening.

[0003]

As described above, the piezoelectric constant d
As is well known, the piezoelectric vibrator 31 has a cantilever beam structure in which one end is fixed to a supporting substrate or a fixed substrate because the displacement is made in the direction perpendicular to the stacking direction of the electrodes and the one end is fixed to the supporting substrate or the fixed substrate. However, the rigidity against bending stress is small, and there is a problem that breakage is likely to occur in the step of forming a piezoelectric vibrator with a dicing saw, wire saw, or the like to form a vibrator of a predetermined size.

In order to solve such a problem, Japanese Patent Publication No. 6-
As seen in Japanese Patent No. 226971, a piezoelectric constant laminated with a piezoelectric material such that an electrode forming one pole and an electrode forming the other pole wrap in the central region, and each is exposed only at one end. It is proposed that the lower end of the piezoelectric vibrator of d33 is attached to a fixed substrate so as to have the same pitch as the arrangement pitch of the pressure generating chambers of the flow path unit.

The piezoelectric vibrator having the piezoelectric constant d33 has the advantages that the displacement efficiency is high and the size can be reduced as compared with the piezoelectric vibrator having the piezoelectric constant d31. A piezoelectric vibrator having a piezoelectric constant d33 is usually formed in a multilayer structure in which a green sheet of a piezoelectric material is exposed on one side with an internal electrode that serves as one pole, and the other side is embedded in the green sheet.
It is constituted by firing this.

[0006]

However, in order to increase the recording density of the ink jet type recording head, when the arrangement pitch of the pressure generating chambers decreases, the size of the piezoelectric vibrator also decreases in proportion. On the other hand, the relative error between the internal electrode and the piezoelectric material in the stacking process is usually about 0.2 mm, and the ratio occupied by the region where only one internal electrode is formed becomes large. For example, as shown in FIG. 7, when the length L0 of the long side is 0.8 mm and the width W0 of the short side is about 0.06 mm, a region where the internal electrodes of both poles wrap, that is, a piezoelectric vibration occurs. The length of the active region A involved is 0.4 mm, while the length of the inactive regions B formed at both ends is 0.2 mm, and the inactive region occupies almost 1/2. Since the inactive region acts as a restraint region with respect to the active region, there are problems that the displacement amount per unit voltage becomes small and unnecessary internal stress is generated in the piezoelectric vibrator.

The present invention has been made in view of the above problems, and its purpose is to reduce the restraining force in the inactive portion as much as possible to improve the displacement efficiency and increase the internal stress. lowering the invention is to provide a pressure electrostatic transducer unit is Ru can. Another object of the present invention is to provide the piezoelectric vibrator unit described above.
The present invention relates to an inkjet recording head that uses a printer.

[0008]

In order to solve such a problem, the invention of claim 1 has an electrode in which one pole and an electrode in the other pole have an overlapping region only in a central region,
Further, each of them is laminated together with the piezoelectric material so as to be exposed only on one side surface, and an active area displacing in the laminating direction of the electrodes is formed in the central portion, and an inactive area not involved in the displacement is formed on each side surface side. In a piezoelectric vibrator unit in which a plurality of piezoelectric vibrators are fixed to a fixed substrate at a fixed pitch, a surface extending on both sides of each pole where the electrodes are exposed extends in the displacement direction of the piezoelectric vibrator. A cutout is formed, and a conductive layer for external connection, which connects the electrodes in parallel, is formed on a protrusion outside the cutout. According to a third aspect of the present invention, the electrode forming one pole and the electrode forming the other pole have an overlapping region only in the central region, and are laminated together with the piezoelectric material so as to be exposed only on one side surface. , A plurality of piezoelectric vibrators having an active region, which is displaced in the stacking direction of the electrodes, in the central portion, and inactive regions that do not participate in the displacement, which are formed on the respective side surfaces, are fixed to a fixed substrate at a fixed pitch. In the piezoelectric vibrator unit, slopes extending in the displacement direction of the piezoelectric vibrator are formed on both sides of the electrodes where the electrodes are exposed, and the electrodes are connected in parallel to the top region formed by the slopes. connecting conductive layer is made form. On the other hand, the invention of claim 5 is
The electrode forming the pole and the electrode forming the other pole are
Have overlapping areas and each only on one side
It is laminated with the piezoelectric material so that it is exposed,
The active area that is displaced in the stacking direction
There is no inactive area on each side surface.
Do not fix multiple vibrators on a fixed substrate at a fixed pitch.
And the displacement of the piezoelectric vibrator unit.
The pressure generating chamber whose volume expands and contracts due to the elastic plate,
A nozzle opening that communicates with the pressure generating chamber to eject ink droplets,
A reservoir that receives ink supply from the outside, and the pressure
Equipped with an ink supply port that connects the force generation chamber and the reservoir
Inkjet recording device consisting of
In the battery, the electrodes of each pole of the piezoelectric vibrator are
Extend in the displacement direction of the piezoelectric vibrator on both sides where the poles are exposed.
A notch is formed on the outer side of the notch
A conductive layer for external connection that connects the electrodes in parallel is formed.
There is. According to the invention of claim 6, the electrode forming one pole and the other
The electrode forming the pole has an overlapping area only in the central area,
Piezoelectric material so that each one is exposed only on one side
Active that is laminated together with the electrode and is displaced in the laminating direction of the electrode.
Inactive regions that do not participate in displacement are located in the central area.
A plurality of piezoelectric vibrators formed on the side surface side of the
Piezoelectric vibrator unit fixed on a fixed substrate at a pitch
And the elastic plate that receives the displacement of the piezoelectric vibrator
Expanding and contracting pressure generating chamber, communicating with the pressure generating chamber
Nozzle openings for ejecting ink droplets, external ink supply
Reservoir for receiving supply, the pressure generating chamber and the reservoir
A flow path unit having an ink supply port for connecting to the
In an ink jet recording head consisting of
Surfaces on both sides of each pole of the vibrator where the electrodes are exposed
Is formed with a slope extending in the displacement direction of the piezoelectric vibrator,
The electrodes are arranged in parallel in the top region formed by the slopes.
A conductive layer for external connection for connection is formed.

[0009]

[Action] For <br/> the inactive region of the side surface side of the restraining portion is reduced, improved Displacement efficiency also decreases the stress at the boundary of the active region and inactive region.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments shown below will be described below. FIG. 1 shows an embodiment of a recording head using the piezoelectric vibrator unit of the present invention. In the figure, reference numeral 1 is a piezoelectric vibration unit characterized by the present invention, and the piezoelectric vibrators 2 and 2 are shown. 2 are exposed on only one side surface, and are formed by laminating an electrode 3 forming one pole and an electrode 4 forming the other pole, which are overlapped in the central region, inside a piezoelectric material 5, and the lower end is made of a rigid material. It is configured by being fixed to a fixing base 6 made of a high material.

On the side surface where the internal electrodes 3 and 4 are exposed,
As shown in FIG. 2, grooves 7 and 8 having a constant width W1 extending in the displacement direction and having a depth about the width of the inactive region are formed in the central portion. The conductive layer 10 extending from at least the electrode formation region through the lower surface of the piezoelectric vibrator 2 to the middle of the other surface is formed on the convex portions 9 and 9 where the electrode 3 forming one pole of the piezoelectric vibrator 2 is exposed. Is formed, and the electrodes forming the other pole of the piezoelectric vibrator 2 are exposed to the extent that a constant gap can be formed at least between the electrode forming region and the conductive layer 10 on the convex portions 11 and 11. The conductive layer 12 is formed up to the position.

An adhesive is applied to the side of the conductive layer 10 that wraps around the other surface and is fixed to the fixed substrate 13. Since the conductive layers 10 and 12 are located close to each other on one surface,
A drive signal can be supplied to the piezoelectric vibrator 2 by abutting the conductive pattern of the flexible cable 14 also serving as a circuit board and fixing it by soldering or the like.

The piezoelectric vibrating unit 1 configured as described above
Is a head holder 25 to which a pressure generating chamber 21, an ink supply port 22, and a flow path unit 24 forming a reservoir 23 are fixed, and the tip of the piezoelectric vibrator 2 is fixed to the head holder 25 via a fixed substrate 13. It is abutted and fixed to the elastic plate 26 forming the ink jet recording head.
Reference numeral 27 in the drawing indicates a nozzle opening.

In this embodiment, when a driving signal is supplied to the piezoelectric vibrator 2 to charge the piezoelectric vibrator 2, a region where the internal electrodes 3 and 4 of the piezoelectric vibrator 2 overlap, that is, an active region is expanded, and the inside of the other one is also expanded. Although the side regions where only the electrodes are present do not participate in the extension, since the grooves 7 and 8 are formed here and the rigidity is weakened, the restraining force becomes small, and the piezoelectric vibrator 2 has the grooves 7 and 8. The displacement is large as compared with the case where no is formed. The pressure generating chamber 2 is generated by the extension of the piezoelectric vibrator 2.
1 contracts to pressurize the ink and eject ink droplets from the nozzle openings 27.

When the supply of the drive signal is stopped after a lapse of a predetermined time, the piezoelectric vibrator 2 contracts to its original state and the pressure generating chamber 21 expands, and the reservoir 2 is supplied through the ink supply port 22.
The ink No. 3 flows into the pressure generating chamber 21 and prepares for the next ink droplet ejection.

As described above, in the piezoelectric vibrator 2, since the rigidity of the inactive regions on both sides is weakened, the displacement efficiency is high,
Further, the stress at the boundary between the inactive region and the active region is reduced, and the piezoelectric vibrator 2 can be prevented from fatigue.

Next, a method of manufacturing the above-described piezoelectric vibrator unit will be described. The inner electrode 30 forming one pole and the inner electrode 31 forming the other pole are wrapped in the central region,
Moreover, a piezoelectric vibrating plate 33 laminated inside the piezoelectric material 32 is prepared so that each is exposed only at one end, and one end of this is fixed to a fixed base 34 (FIG. 3 (I)).

The projections 9 and 11 are formed at a pitch for cutting out as a piezoelectric vibrator, in a stacking direction of the internal electrodes 30 and 31, that is, in a displacement direction as a piezoelectric vibrator, preferably to a depth that does not reach the other electrode. A groove 35 having a width capable of forming a groove is formed on both sides (FIG. 3 (II)).

Dicing saws or wire saws are used to form slits 37, 37 having a depth such that at least the internal electrodes 30, 31 can be separated so that the piezoelectric vibrator 2 has a necessary width, and the comb teeth are divided. 3 (III)).

Then, a piezoelectric layer is completed by forming a conductive layer on each side and fixing it to a fixed substrate.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the center of the surface where only one of the internal electrodes 3 and 4 of the piezoelectric vibrator is exposed is the apex, and the width direction is Slopes 4 on both sides of the surface that do not reach the other internal electrode
0, 40, 40, 40 are formed, and external connection electrodes 41, 41 are formed near the top.

Also in this embodiment, since the inactive regions B, B are also shaved by the slopes, the proportion of the entire region is reduced, so that the degree of restraint by the inactive regions is reduced and the displacement efficiency is improved. Since the internal stress can be reduced and the external electrode formation surface is formed of two surfaces, the external connection electrodes 41, 41 can be highly reliably deposited by vapor deposition or the like.
Can be formed.

FIG. 5 shows a method of manufacturing the above-described piezoelectric vibrator unit, in which a "V" -shaped groove is formed from a position where the other ends of the internal electrodes 30, 31 exposed at one end are not exposed. 50 is formed so that the sum of the width of the slit for dividing the teeth and the width of the piezoelectric vibrator serves as a pitch and is symmetrical (I). Then, the slits 51, 51, 51, so that the deepest part of the “V” -shaped grooves 50, 50 are the center lines,
Forming (II).

Although the slopes are formed symmetrically on both sides from the center in the above embodiment, a single slope 42 is formed symmetrically as shown in FIG. The external connection electrode 43 may be provided in the region near the top of the.

[0025]

As described above, according to the present invention,
Since the ratio of the inactive area on the side surface that becomes the bunch decreases ,
The displacement efficiency is improved, it is possible to reduce the stress at the boundary of the active region and an inactive region at the same time.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an ink jet recording head using a piezoelectric vibrator unit of the present invention.

2A and 2B are respectively a perspective view and a top view showing an embodiment of a piezoelectric vibrator.

3 (A) to (III) are diagrams showing an embodiment of a method of manufacturing a piezoelectric vibrator unit according to the present invention.

4A and 4B are respectively a perspective view and a top view showing another embodiment of the piezoelectric vibrator.

5 (I) and (II) are diagrams showing an embodiment of a method of manufacturing the piezoelectric vibrator unit, respectively.

FIG. 6 is a top view showing an example of the piezoelectric vibrator.

FIG. 7 is a top view showing a conventional piezoelectric vibrator having a piezoelectric constant d33.

[Explanation of symbols]

1 Piezoelectric vibration unit 2 Piezoelectric vibrator 3, 4 internal electrodes 5 Piezoelectric material 6 fixed stand 7, 8 groove 9, 11 convex 10, 12 conductive layer 13 Flexible cable

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 H01L 41/09

Claims (6)

(57) [Claims] 1. An electrode forming one pole and an electrode forming the other pole have an overlapping region only in a central region, and are laminated together with a piezoelectric material so as to be exposed only on one side surface, and the electrode is formed. A piezoelectric vibrator in which a plurality of piezoelectric vibrators each having an active region displacing in the stacking direction in the center and an inactive region not involved in the displacement formed on each side surface are fixed to a fixed substrate at a constant pitch. In the unit, a notch portion extending in the displacement direction of the piezoelectric vibrator is formed on both surfaces of each pole where the electrodes are exposed, and the electrodes are connected in parallel to the protrusions outside the notch portion. A piezoelectric vibrator unit in which a conductive layer for connection is formed. 2. The piezoelectric vibrator unit according to claim 1, wherein the cutout portion is formed by a groove. 3. An electrode forming one pole and an electrode forming the other pole have an overlapping region only in a central region, and are laminated together with a piezoelectric material so as to be exposed only on one side surface, and the electrode is formed. A piezoelectric vibrator in which a plurality of piezoelectric vibrators each having an active region displacing in the stacking direction in the center and an inactive region not involved in the displacement formed on each side surface are fixed to a fixed substrate at a constant pitch. In the unit, slopes extending in the displacement direction of the piezoelectric vibrator are formed on both sides of the electrode where the electrodes are exposed, and a conductive material for external connection that connects the electrodes in parallel to a top region formed by the slopes. Piezoelectric vibrator unit in which layers are formed. 4. The piezoelectric vibrator unit according to claim 3, wherein the top region is formed in a central region in the width direction of the side surface. 5. An electrode forming one pole and an electrode forming the other pole have an overlapping region only in a central region, and are laminated together with a piezoelectric material so as to be exposed only on one side surface, and the electrode is formed. A piezoelectric vibrator in which a plurality of piezoelectric vibrators each having an active region displacing in the stacking direction in the center and an inactive region not involved in the displacement formed on each side surface are fixed to a fixed substrate at a constant pitch. A unit, a pressure generating chamber whose volume is expanded and contracted by an elastic plate that receives displacement of the piezoelectric vibrator, a nozzle opening that communicates with the pressure generating chamber to eject ink droplets, a reservoir that receives ink supplied from the outside, And a flow path unit having an ink supply port that connects the pressure generating chamber and the reservoir, the ink jet recording head comprising: A notch portion extending in the displacement direction of the piezoelectric vibrator is formed on both surfaces where the pole is exposed, and a conductive layer for external connection that connects the electrodes in parallel is formed on a convex portion outside the notch portion. Inkjet recording head. 6. An electrode forming one pole and an electrode forming the other pole have an overlapping region only in a central region, and are laminated together with a piezoelectric material so as to be exposed only on one side surface, and the electrode is formed. A piezoelectric vibrator in which a plurality of piezoelectric vibrators each having an active region displacing in the stacking direction in the center and an inactive region not involved in the displacement formed on each side surface are fixed to a fixed substrate at a constant pitch. A unit, a pressure generating chamber whose volume is expanded and contracted by an elastic plate that receives displacement of the piezoelectric vibrator, a nozzle opening that communicates with the pressure generating chamber to eject ink droplets, a reservoir that receives ink supplied from the outside, And a flow path unit having an ink supply port that connects the pressure generating chamber and the reservoir, the ink jet recording head comprising: An ink jet type in which inclined surfaces extending in the displacement direction of the piezoelectric vibrator are formed on both surfaces where the poles are exposed, and a conductive layer for external connection that connects the electrodes in parallel is formed in a top region formed by the inclined surfaces. Recording head.