JP3102064B2 - Piezoelectric displacement unit and method of manufacturing the same - 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 displacement unit in which a plurality of piezoelectric displacement elements suitable for an ink jet recording head and the like are fixed to a base.

[0002]

2. Description of the Related Art An ink jet recording head is constructed so that a pressure chamber is displaced by a piezoelectric displacement element to pressurize ink and eject ink droplets from nozzle openings.
Since such a piezoelectric displacement element usually needs to be driven at a voltage of 200 to 300 volts, sufficient electric insulation treatment is required to incorporate the piezoelectric displacement element in an environment where a conductive liquid such as ink is handled, and the structure is complicated. There is a problem of inviting.

To solve this problem, for example, Japanese Patent Application Laid-Open
As disclosed in JP-A-63-295269, the piezoelectric layer is exposed such that the electrode layer serving as one pole is exposed only at one end in the stretching direction, and the electrode layer serving as the other pole is exposed only at the other end. A piezoelectric displacement element laminated on almost the whole material has been proposed. According to this, a displacement capable of ejecting ink droplets at a voltage of about 10 volts can be obtained, and electrical insulation can be easily ensured.

[0004] However, in order to pressurize the pressure chamber with such a piezoelectric displacement element, it is necessary to fix the piezoelectric displacement element to a base. Therefore, when trying to fix the end face of the piezoelectric displacement element, it is difficult to obtain an adhesive strength because the cross-sectional area is extremely small.

When the side surface is fixed to solve this problem, the bonding area is displaced by the expansion and contraction of the piezoelectric displacement element, and a shearing force acts on the bonding layer. However, there is a problem that the displacement amount of the piezoelectric displacement element with respect to the portion and the pressing force change or become inoperable, and the reliability is reduced.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a novel piezoelectric displacement unit capable of ensuring the reliability of an adhesive layer.

Another object of the present invention is to propose a method for manufacturing the piezoelectric displacement element.

[0008]

According to the present invention, there is provided a piezoelectric displacement element which expands and contracts in the axial direction by alternately disposing electrode layers forming one pole and electrode layers forming the other pole in a piezoelectric material. In a piezoelectric displacement unit in which the piezoelectric displacement element is fixed to a fixed substrate via an adhesive layer so that one end is a free end, an electric field generated by the electrode layer acts on the piezoelectric material on the free end. The electrode layer is formed in a region facing the adhesive layer so that an electric field generated by the electrode layer does not act on the piezoelectric material.

[0009]

The piezoelectric displacement element has its inactive portion fixed to the base, so that only the active portion expands and contracts, and the inactive portion, which is a fixed region, does not cause relative displacement between the base and the base. The adhesive layer of the agent does not receive shearing force.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; FIG. 1 shows an embodiment of a piezoelectric displacement element according to the present invention. The piezoelectric displacement elements 1, 1, 1 ‥‥ are arranged at pitches of driven parts, for example, an array of pressure generating chambers, which will be described later. In accordance with the pitch, the other half of the piezoelectric displacement elements 1, 1, 1,... Is bonded to the base 3 as a bonding area 2 so that one half of the expansion / contraction direction (arrow A in the figure) is a free end area. Is fixed.

The base 3 has a projection 3 in a region to be the joining region 2.
a is formed so as to form a gap 4 with the free end region of the piezoelectric displacement element 1.

These piezoelectric displacement elements 1, 1, 1,.
The electrode layer 5 serving as one pole and the electrode layer 6 serving as the other are laminated so as to wrap with, for example, a piezoelectric titanate / lead zirconate-based composite perovskite piezoelectric material 7 therebetween to form an active portion. In the region, an inactive portion is formed by extending the above-mentioned one electrode layer 5 and laminating the electrode layer 5 so that only the electrode layer 5 exists in the piezoelectric material.

The electrode layer 5 of one pole, which exists only in the inactive portion, has a free end side tip region having a predetermined length ΔL.
The length of the piezoelectric displacement element 1 is shorter than that of the piezoelectric displacement element 1, and the distal end (the upper end in the figure) is buried in the piezoelectric material 7 and is exposed from the end face 1 a on the fixed end side.

The other electrode layer 6 which exists only in the active portion
Is formed such that the free end side tip is exposed from the end face 1b.

The end faces 1a and 1b where the electrode layer 5 of one pole and the electrode layer 6 of the other pole are exposed are provided with a conductive layer 8,
9 (FIG. 2 (f)) are formed, and the plurality of electrode layers 5 of one pole are connected in parallel by the conductive layer 8, and the plurality of electrode layers 6 of the other pole are connected in parallel by the conductive layer 9. I have.

FIG. 2 shows an embodiment of a method of manufacturing the above-described piezoelectric displacement element. The piezoelectric material such as a titanate / lead zirconate-based composite perovskite prepared in a paste form on the surface of the surface plate 10 is shown in FIG. Is thinly applied to form a piezoelectric layer 7-1 (FIG. 2A).

An electrode layer 5 serving as a first pole is formed on the surface of the piezoelectric layer 7-1 by vapor deposition of a conductive material or application of a conductive material to the other end so that one end is left with a predetermined width L. (FIG. 2B).

The piezoelectric layer 7-2 is formed so as to fill the electrode layer non-formation region (the region of width L) and cover the first electrode layer 5 (FIG. 2C).

A second electrode layer 6 is formed from one end to a region where an active portion is to be formed in the same manner as the first electrode layer 5 (FIG. 2D).

A second piezoelectric layer 7-3 is formed by applying a thin piezoelectric material so as to cover the exposed surface of the second piezoelectric layer 7-2 and to cover the second electrode layer 6. As shown in FIG. 2 (b)
2 (d) are repeated for the number of layers to be formed to form a laminate (FIG. 2 (e)), and the laminate is dried to a predetermined temperature, for example, 1000 ° C. to 12 ° C.
Bake at 00 ° C for about 1 hour.

A conductive material is applied to the surface of the piezoelectric block 11 having the above structure in which one pole and the other pole are exposed to form conductive layers 8 and 9. When fixed to the base 3 with an adhesive or the like so that a region where only the electrode layer 5 exists is a fixed region, and cut at a predetermined width in parallel to the displacement direction from the conductive layer 9 side, the piezoelectric displacement unit described above is obtained. Is completed.

As shown in FIG. 3, the piezoelectric displacement element has an end face 1b on the free end side, and a pressure chamber 2 communicating with a common ink chamber 20 and a nozzle opening 22 of a nozzle plate 21.
3 is set via the base 3 so as to come into contact with the spring plate member 24 forming the spring plate member 3 and is incorporated in the ink jet recording head.

When a drive signal is applied to each of the electrode layers 5 and 6 of the piezoelectric displacement element 1 incorporated in the ink jet recording head, the electrode layer 5 forming one pole of the piezoelectric material 7 is formed.
Only the region where the electrode layer 6 which forms the other pole opposes expands and contracts under the action of the electric field, and presses the spring plate 24 toward the pressure chamber or expands it outward. Thereby, the pressure chamber 2
The ink of No. 3 is pressurized and ejected from the nozzle opening 22 as ink droplets, and the ink of the common ink chamber 20 is sucked and supplied to the pressure chamber 23.

Incidentally, the piezoelectric material 7 in the region where only the electrode layer 5 forming one pole is present is not affected by an electric field, and therefore does not expand and contract. Therefore, the piezoelectric material 7 is not in contact with the base 3 of the piezoelectric displacement element 1. A shear force due to expansion and contraction does not act on the joining region 2, thereby preventing the adhesive in the joining region 2 from being fatigued or cracked.

A plurality of piezoelectric displacement units in which the ratio of the active part to the inactive part is different as shown in Table 1 and the inactive part is fixed to the base with an adhesive by using the inactive part as a bonding area are prepared (implemented). Examples 1 to 4), when observing the state of displacement and peeling of the adhesive, it was found that the adhesive was not displaced and did not peel off, and that the piezoelectric displacement element was displaced in a single direction with directivity. That was confirmed.

[0026]

[Table 1]

[0027]

As described above, in the present invention,
An active part where the electric field from the electrode layer acts on the piezoelectric material is formed on the free end side, and an electrode layer is formed on the area facing the adhesive layer so that an inactive part where the electric field from the electrode layer does not act on the piezoelectric material is formed. Therefore, regardless of the expansion and contraction of the piezoelectric displacement element, the fixed area of the piezoelectric displacement element is prevented from being relatively displaced between the base and the base, so that fatigue and cracks of the adhesive layer can be prevented. Units can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a piezoelectric displacement unit of the present invention.

FIGS. 2A to 2F are diagrams showing a method of manufacturing the piezoelectric displacement unit according to the first embodiment.

FIG. 3 is a view showing one embodiment of an ink jet recording head using the same piezoelectric displacement unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric displacement element 2 Joining area 3 Base 3a Convex part 4 Gap 5, 6 Electrode layer 7 Piezoelectric material 8, 9 Conductive layer

Claims (9)

(57) [Claims] An electrode layer forming one pole and an electrode layer forming the other pole are alternately arranged in a piezoelectric material to form a piezoelectric displacement element which expands and contracts in an axial direction. In a piezoelectric displacement unit fixed to a base via an adhesive layer so as to be a free end, an active portion where an electric field by the electrode layer acts on the piezoelectric material is provided on the free end side, and the active layer is provided on the adhesive layer. A piezoelectric displacement unit in which the electrode layer is formed such that an inactive portion where an electric field generated by the electrode layer does not act on the piezoelectric material is formed in an opposed region. 2. An electrode layer forming one of the poles is exposed on an end face of the inactive portion in the direction of expansion and contraction of the piezoelectric displacement element, near the free end side end face and up to a position not exposed from the end face. 2. The piezoelectric displacement unit according to claim 1, wherein the extended electrode layer forming the other pole is formed on the active portion so as to be exposed at the free end. 3. 3. The piezoelectric displacement unit according to claim 2, wherein a conductive layer that connects the electrode layers in parallel is formed on an end face of the piezoelectric displacement element in the direction of expansion and contraction. 4. The piezoelectric displacement unit according to claim 3, wherein a drive signal is applied to the electrode layer via the conductive layer. 5. The piezoelectric displacement unit according to claim 2, wherein the piezoelectric material is filled in a region where the electrode layer is not formed. 6. The piezoelectric displacement unit according to claim 1, wherein the base has a convex portion in a region of the adhesive layer. 7. The piezoelectric displacement unit according to claim 1, wherein a tip of the base on the free end side of the piezoelectric displacement element abuts on a driven member. 8. A step of forming a first electrode layer on the surface of the piezoelectric layer so as to expose the piezoelectric layer at one end, and filling a first electrode layer non-formation region with the first electrode layer. Forming a piezoelectric layer so as to cover the first electrode layer, forming a second electrode layer in a region serving as an active portion so as to be exposed from the other end, Repeating the steps of forming a piezoelectric material layer so as to cover the formation region and cover the second electrode layer in accordance with the number of layers to be formed, and firing the laminate. Forming a conductive layer on the surface where the first and second electrode layers are exposed, and fixing the block to a base such that a region where only the first electrode layer is present is a fixed region. A method for manufacturing a piezoelectric displacement unit comprising: 9. The method according to claim 8, further comprising a step of cutting only the block at a predetermined pitch.