JPH05198861A - Laminated piezoelectric displacement element and ink jet type print head - Google Patents

Abstract

PURPOSE:To obtain a laminated piezoelectric displacement element wherein necessary displacement amount can be obtained by a low voltage, distortion is small, and therefore electrode peeling on the interface between the inner layer and the outermost layer is hardly generated. CONSTITUTION:Piezoelectric bodies 3 are alternately arranged in a sandwich type, in the manner in which a conducting layer 1 constituting one electrode and a conducting layer 2 constituting the other electrode are in parallel with each other. The part position sandwiched by the conducting layer 1, 2 is an active part 6, and the part positions 5, 5a which are not sandwiched are inative parts. In order that an electric field may be applied also to the outermost layer 4, the outermost electrodes 10b, 10a are constituted on the outermost layer end surfaces, so as to be in parallel with the conducting layers 1, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric displacement element used for a print head of an ink jet printer and an ink jet print head using the same.

[0002]

2. Description of the Related Art A conventional ink jet print head is
As shown in Japanese Examined Patent Publication No. 60-8953, a plurality of nozzle openings are formed on the wall surface of a container constituting an ink tank, and piezoelectric elements are arranged so that the expansion and contraction directions are aligned so as to face each nozzle opening. It is constructed and set up. This print head applies a drive signal to a piezoelectric element to expand and contract the piezoelectric element, and the dynamic pressure of ink generated at this time causes ink droplets to be ejected from nozzle openings to form dots on printing paper.

In a print head of this type,
It is desirable that droplet formation efficiency and flight force are large. However, since the unit length of the piezoelectric element and the expansion / contraction rate per unit voltage are extremely small, it is necessary to apply a high voltage in order to obtain the flying force required for printing, which complicates the drive circuit and electrical insulation measures. The problem is that

In order to solve such a problem, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Patent Laid-Open No. 3-295269, there is proposed a laminated piezoelectric displacement element for an inkjet print head in which electrodes and piezoelectric materials are alternately laminated in a sandwich shape. According to this laminated piezoelectric displacement element, the distance between the electrodes can be made as small as possible, so that the voltage of the drive signal can be lowered.

[0005]

However, it is difficult to form such a laminated piezoelectric displacement element into a small size, and there is a problem that its application is limited.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminated piezoelectric displacement element having high operation efficiency and high reliability, and to provide an ink jet type print head capable of easily miniaturizing the piezoelectric element. ..

[0007]

A laminated piezoelectric displacement element in which a piezoelectric body and an electrode are alternately laminated, and an electrode is provided on an end face of an outermost layer in parallel with an inner electrode so that an electric field is applied to the outermost layer. Is configured.

In an ink jet type print head in which a piezoelectric element is arranged corresponding to a nozzle opening, and ink is discharged to the outside from the nozzle opening by a drive signal to the piezoelectric element, the piezoelectric element is at least a piezoelectric body and an electrode. Is a laminated piezoelectric displacement element in which and are alternately laminated, and is characterized in that an electrode is also formed on the end face of the outermost layer in parallel with the internal electrode so that an electric field is applied to the outermost layer.

[0009]

1 is a perspective view showing an embodiment of a laminated piezoelectric displacement element of the present invention. In the figure, 1 is a conductive layer that constitutes one of the electrodes. Reference numeral 2 is a conductive layer that constitutes the other electrode, and the conductive layers are alternately arranged in parallel with each other in a piezoelectric body 3, for example, a titanate / lead zirconate-based composite perovskite ceramic. The portion sandwiched between the conductive layers 1 and 2 is the inner layer. Reference numeral 90 denotes a dummy electrode layer, which does not generate an electric field for displacing the laminated piezoelectric displacement element, and when manufacturing the laminated piezoelectric displacement element, the number of layers of the active portion 6 and the inactive portion 5 is the same. It is necessary to prevent distortion such as warpage. The conductive layer 1 and the dummy electrode layer 90, which are one of the electrodes, are connected to the outermost electrode 10a, and the conductive layer 2 that is the other electrode is connected to the other outermost electrode 10b. The outermost electrodes 10a and 10b become positive or negative, and accordingly, the conductive layers 1 and 2 are electrically arranged in parallel. The inactive portion 5 is necessary for fixing, and its length is determined by fixing conditions. The active portion 6 is a portion that is actually displaced in the direction of the end face 7 in the displacement direction when an electric field is applied. The inactive portion 5a is necessary to prevent the conductive layer 1 and the outermost electrode 10b from being connected to each other.

At least in the active portion 6, the outermost layer 4 is the outermost electrode 10a and the conductive layer 2 or the outermost electrode 10b and the conductive layer 1.
It is configured to be sandwiched between. For this reason, an electric field is applied to the outermost layer and the outermost layer is also displaced, so that the required amount of displacement can be obtained at a low voltage and displacement with less strain can be obtained.Therefore, peeling at the boundary between the outermost layer and the inner layer is also possible. Less likely to occur.

Since the number of laminated layers is odd in FIG. 1, the outermost layer 4 is the outermost electrode 10a and the conductive layer 2 or the outermost electrode 10.
It was configured to be sandwiched between b and the conductive layer 1. However, as shown in FIG. 2, when the number of stacked layers is an even number, both outermost layers 4 can be configured to be sandwiched between the outermost electrode 10 b and the conductive layer 2 at least in the active portion 6. Similarly, depending on the number of layers, both outermost layers 4 may be sandwiched between the outermost electrode 10a and the conductive layer 1. The outermost electrodes 10a, 10b are formed by vapor deposition of gold, copper, or the like, have good conductivity, have few breaks during processing, and can be thinly cut for high density. When the outermost electrodes 10a and 10b are formed of a thick material such as plating, they are often dragged during cutting and chipped or burred. In order to increase the adhesion with the laminated piezoelectric displacement element, nickel-chromium is first vapor-deposited with a thickness of about 0.125 μm, and gold with a sheet resistance of 1Ω or less is vapor-deposited thereon. For vapor deposition of copper, nickel
Use chrome instead of chrome. The thickness of gold and copper is
If it was made too thick to reduce the resistance value, there were many chips and burrs during processing, similar to plating. About 0.5 μm
The rank seems appropriate.

As shown in FIG. 3A, such a laminated piezoelectric displacement element block 20 is bonded to the base 8. The laminated piezoelectric displacement element block 20 thus bonded is cut into a predetermined width and arranged at regular intervals to form a laminated piezoelectric displacement element row 21 as shown in FIG. 3B. And the outermost electrode 10
An independent lead member 32 is connected to a and the outermost electrode 10b
A common lead member 31 is connected to. In addition, this FIG.
In (a), the independent lead member 32 is directly bonded to the outermost electrode 10a, but wiring is performed on the base 8 to make the adhesive between the laminated piezoelectric displacement element block 20 and the base 8 conductive. If an object is used or an adhesive is thinned and pressure is applied so that conduction can be obtained, the independent lead member 32 may be joined to the base 8, and the laminated piezoelectric displacement may be directly joined to the laminated piezoelectric displacement element. Without falling down or scratching the element,
Workability has also improved significantly. If there is no electrode on the outermost layer end face of the outermost electrode 10b, the common lead member 31 is connected to the end face 7 in the displacement direction. The spring plate member 45 is bonded to the end face 7 in the displacement direction as shown in FIG. 6, and is not suitable for connecting the lead member 31. Furthermore, if the common lead member is connected to the active portion 6 where the laminated piezoelectric displacement element actually displaces, it is not suitable for connection because it inhibits displacement. In order to escape this, the outermost electrode 10b is extended to the portion of the inactive portion 5, and the inactive portion 5 is connected.

The operation of the laminated piezoelectric displacement element will be described with reference to FIG. When the charging switch 61 is turned on as shown in FIG. 4A, the conductive layers 1 and 2 of the active portion 6, the outermost electrode 10a and the conductive layer 2, and the outermost electrode 10b and the conductive layer 1 are respectively connected. An electric field is applied. Then, the piezoelectric body 3 of the active portion 6 is moved to the arrow 5
Shrink in the direction of 1. Discharge switch 6 as shown in FIG.
When 2 is entered, the electric field between the electrodes is released, and the piezoelectric body 3 of the active portion 6 extends in the direction of arrow 52 and returns to the length before applying the electric field.

On the other hand, the case where the outermost electrode is not formed on the end face of the outermost layer will be described with reference to FIG. As shown in FIG. 5A, the piezoelectric bodies 7 are alternately arranged so that the conductive layers 71 and 72 are parallel to each other.
It is also the case that they are arranged in a sandwich shape in 3. However, the outermost electrodes 80 (a) and 80 (b) are not formed on the end face of the outermost layer.

When a voltage is applied to such a laminated piezoelectric displacement element, the piezoelectric body 73 sandwiched between the conductive layers 71 and 72 contracts in the direction of arrow 91 as shown in FIG. 5B, but the outermost layer has an electric field. Since no is added, the displacement type becomes distorted only by being dragged. When such a distorted displacement occurs, the adhesive force between the end face 7 and the spring plate member 45 (FIG. 6) in the displacement direction weakens and peels off, or peeling occurs at the electrode at the boundary between the outermost layer and the inner layer. ..

When the laminated piezoelectric displacement element is applied to a Kaiser type laminated piezoelectric displacement element longitudinal vibration type head which is an ink jet recording apparatus shown in FIG. 6A, a required displacement amount can be obtained at a low voltage. Further, it is possible to obtain a displacement with less distortion. Therefore, an enlarged view of the driving unit when FIG. 6A is cut along the plane A and viewed from the Z direction is shown in FIG. 6B, and a process until ink droplets are ejected from the nozzle openings 44 will be described.

In FIG. 6B, when a voltage is applied to the laminated piezoelectric displacement element 41 facing the nozzle opening formed in the nozzle plate 44a on which dots are to be formed, the laminated piezoelectric displacement element 41 has a spring rich in elasticity. It is possible to extend the plate member 45 while deforming it, to push out the partition wall 42 disposed on the facing surface of the laminated piezoelectric displacement element and the ink 43 in the partition wall, and eject the ink droplet from the nozzle opening.

[0018]

As described above, the piezoelectric element in which the piezoelectric material and the conductive material are alternately laminated in layers,
By forming an electrode on the end face of the outermost layer in parallel with the inner electrode, an electric field is also applied to the outermost layer, so that the required displacement amount can be obtained at a low voltage and the displacement with less strain can be obtained. Peeling at the boundary with the inner layer was less likely to occur.

A piezoelectric element in which a piezoelectric material and a conductive material are alternately laminated in layers is fixed at one end to the base, and the other end is arranged as a free end corresponding to the nozzle opening, and parallel to the internal electrodes. Since the electric field is also applied to the outermost layer by configuring the electrode on the end face of the outermost layer, the necessary displacement amount can be obtained at a low voltage and the displacement with less strain can be obtained. Peeling at the border is unlikely to occur,
Furthermore, the lead member can be easily routed, connection can be made without hindering displacement, and workability is improved, so that a piezoelectric element array suitable for placement in the inkjet print head can be obtained. It was

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a laminated piezoelectric displacement element of the present invention.

FIG. 2 is a perspective view showing another embodiment of the laminated piezoelectric displacement element of the present invention.

3A is a perspective view showing an embodiment of a fixing structure of a laminated piezoelectric displacement element block having the layer structure of FIG. 1. FIG.
FIG. 3B is a partial perspective view showing a laminated piezoelectric displacement element row and a lead member obtained by cutting the laminated piezoelectric displacement element block of FIG.

4A and 4B are explanatory views of the operation of the laminated piezoelectric displacement element having the layer structure of FIG.

FIG. 5A is a perspective view showing an example of a laminated piezoelectric displacement element in which an electrode is not formed on the end face of the outermost layer. (B)
[FIG. 6] is an explanatory diagram of an operation of the laminated piezoelectric displacement element in which an electrode is not formed on the end face of the outermost layer.

6A is a structural diagram showing a vertical vibration type inkjet head unit of a Kaiser type laminated piezoelectric displacement element using the laminated piezoelectric displacement element having the layer structure of FIG. 1. FIG. (B)
6A is an enlarged view of a drive unit when the Kaiser type stacked piezoelectric displacement element longitudinal vibration type inkjet head structure diagram of FIG. 6A is cut on a plane A and viewed from a Z direction. FIG.

[Explanation of symbols]

 1 ... Conductive layer constituting one electrode 2 ... Conductive layer constituting the other electrode 3 ... Piezoelectric body 4 ... Outermost layer 5 ... Inactive portion 5a.・ ・ ・ Inactive part 6 ・ ・ ・ Active part 7 ・ ・ ・ Displacement end face 8 ・ ・ ・ Base 10a ・ ・ ・ Outermost electrode 10b ・ ・ ・ Outermost electrode 20 ・ ・ ・Stacked piezoelectric displacement element block 21 ... Stacked piezoelectric displacement element row 31 .... Common lead member 32 .... Independent lead member 41 .... Stacked piezoelectric displacement element 42 .. Partition wall 43 ... Ink 44 ... Nozzle opening 44a ... Nozzle plate 45 ... Spring plate material 51 ... Arrow 52 .... Arrow 61 .... Charge switch 62・ ・ ・ ・ Discharge switch 71 ・ ・ ・ ・ Conductive layer 72 ・ ・ ・ ・Conductive layer 73 ... Piezoelectric body 74 ... Outermost layer 80a ... Outermost electrode 80b ... Outermost electrode 90 ... Dummy electrode layer

Front page continuation (72) Inventor Munehide Kanaya 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation

Claims (2)

[Claims] 1. A laminated piezoelectric displacement element in which at least a piezoelectric body and electrodes are alternately laminated, and electrodes are formed on the outermost layer end faces in parallel with the internal electrodes so that an electric field is applied to the outermost layers as well. A laminated piezoelectric displacement element characterized by the above. 2. In an ink jet print head in which a piezoelectric element is arranged corresponding to a nozzle opening, and ink is discharged from the nozzle opening to the outside by a drive signal to the piezoelectric element, the piezoelectric element is at least a piezoelectric body. Inkjet printing, which is a laminated piezoelectric displacement element in which electrodes and electrodes are alternately laminated, and electrodes are also formed on the end faces of the outermost layers in parallel with the internal electrodes so that an electric field is applied to the outermost layers. head.