JP3347346B2 - Piezoelectric displacement unit for inkjet recording apparatus and recording head for inkjet recording apparatus - 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 direction of expansion and contraction, 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 the 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 is applied to the bonding layer, thereby causing fatigue, cracks, and peeling of 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.

Further, since the displacement area is restrained by the base, there are problems that the displacement direction is deviated from the axial direction and the displacement speed is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a purpose thereof is to provide a novel piezoelectric displacement unit which ensures the reliability of an adhesive layer and does not hinder the displacement of a piezoelectric displacement element. It is to provide.

Another object of the present invention is to provide a piezoelectric displacement unit as described above.
To provide a recording head for an ink jet recording apparatus using the same .

[0009]

Means for Solving the Problems To achieve such a problem
The present invention relates to a piezoelectric displacement unit for an ink jet recording apparatus according to the present invention.
The knit is formed by alternately laminating a plurality of electrode layers forming one pole, an electrode layer forming the other pole , and a piezoelectric material alternately on one end.
Straight said active portion of an electric field acts on the piezoelectric material, to form a inactive portion at the other end, in the stacking direction of the electrode layer
A plurality of piezoelectric displacement elements that expand and contract in an intersecting direction;
The side surface of the inactive portion of the displacement element is fixed via an adhesive layer.
And the tip of the active portion is positioned with respect to the driven member.
It is composed of a base to be placed.

[0010]

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. In addition, the active portion is released from the restraint of the base by the inactive portion formed slightly on the free end side from the fixed region, so that bending in the displacement direction and reduction in the displacement speed are prevented.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of 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. Less than,
A plurality of piezoelectric displacement elements 1, 1, 1, ‥‥ are fixed to the base 3
This structure is called a piezoelectric displacement unit.

The base 3 has a projection 3
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 of the electrodes 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 tip region on the free end side 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 existing only in the active portion
Is formed such that the free end side tip is exposed from the end face 1b, and the inactive portion side end is located at a position lower than the protrusion 3a by ΔG toward the free end.

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 for manufacturing the above-described piezoelectric displacement element. The piezoelectric material such as a titanate / lead zirconate composite perovskite prepared in paste form on the surface of the surface plate 10 is shown. 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 configured as described above on which one of the poles and the other pole are exposed to form conductive layers 8 and 9. Is fixed to the base 3 with an adhesive or the like so that the region where only the electrode layer 5 exists is a fixed region, and the direction of displacement from the conductive layer 9 side , that is, the direction of a line connecting the free end and the fixed end (hereinafter, referred to as ,
When this is cut at a predetermined width in parallel to the axial direction) , the above-described piezoelectric displacement unit is completed.

As shown in FIG. 3, the piezoelectric displacement element has an end face 1b on its 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 as described above, 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.

By the way, the piezoelectric material 7 in the region where only the electrode layer 5 forming one pole is present is not affected by the 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.

Since an inactive portion protrudes extra by ΔG to the free end side between the joining region 2 and the active portion, that is, the displacement region, the adhesive in the joining region 2 slightly flows out to the free end side. Also remain in the inactive portion of length ΔG,
The displacement area is prevented from being restrained by the base 3.

As a result, the displacement speed of the piezoelectric displacement element of the entire unit can be made uniform, and the displacement direction can be prevented from tilting due to the constraint of one surface of the displacement region. Since the displacement of the active portion is buffered by the inactive portion having the length ΔG, the propagation of the displacement to the base 3 is reduced as much as possible. The influence of the displacement of the displacement element can be prevented.

The piezoelectric displacement element 1 has a relative length of the active portion of 1
When the relative length of the inactive portion is 0.5 to 10, and preferably the length of the inactive portion is about 1 to 3, securing and gain of the bonding strength of the piezoelectric displacement element, that is, displacement amount Is suitable for balancing In addition, the amount of protrusion of the inactive portion toward the free end is preferably about 0.5 mm at the maximum in consideration of displacement efficiency and the flow of the adhesive.

[0029]

As described above, according to the present invention , the active portion is released from the restraint of the base and the expansion and contraction in the longitudinal direction is inhibited.
Can be securely fixed to the base without
Tip of multiple piezoelectric displacement elements in the area to pressurize the ink
Can be positioned.

[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 ΔG Extrusion amount of inactive portion to free end side

Continued on the front page (72) Inventor Shuji Yonekubo 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Tomoaki Abe 3-5-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson (56) References JP-A-3-197049 (JP, A) JP-A-63-218363 (JP, A) JP-A-57-34974 (JP, A) JP-A-60-90770 (JP, A) A) Patent 3041952 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/16

Claims (2)

(57) [Claims] 1. An electrode layer forming one pole, an electrode layer forming the other pole, and a plurality of piezoelectric materials are alternately laminated, and an active portion for applying an electric field to the piezoelectric material is provided on one end side, and on the other end side. While forming an inactive portion, a plurality of piezoelectric displacement elements that expand and contract in a direction perpendicular to the lamination direction of the electrode layers, and fixing the side surface of the inactive portion of the piezoelectric displacement element via an adhesive layer, A piezoelectric displacement unit for an ink jet recording apparatus, comprising: a base for positioning a tip of the active portion with respect to a driven member. 2. A recording head for discharging an ink droplet from a nozzle opening by deforming an elastic wall by a pressing means, wherein the pressing means comprises: an electrode layer forming one pole; an electrode layer forming the other pole; A plurality of piezoelectric materials are alternately laminated, respectively.
An active portion on which an electric field acts on the piezoelectric material on one end side, and an inactive portion formed on the other end side, and a plurality of piezoelectric displacement elements that expand and contract in a direction perpendicular to the laminating direction of the electrode layers; A recording device for an ink jet recording apparatus, comprising a piezoelectric displacement unit comprising: a base for fixing a side surface of the inactive portion of the element via an adhesive layer and positioning a tip of the active portion with respect to the elastic wall. head.